diff --git a/src/meta/agsc.c b/src/meta/agsc.c
index d2f55b42..72629315 100644
--- a/src/meta/agsc.c
+++ b/src/meta/agsc.c
@@ -43,6 +43,7 @@ VGMSTREAM * init_vgmstream_agsc(STREAMFILE *streamFile) {
     vgmstream->coding_type = coding_NGC_DSP;
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_DSP_AGSC;
+    vgmstream->allow_dual_stereo = 1;
 
     for (i=0;i<16;i++) {
         vgmstream->ch[0].adpcm_coef[i]=read_16bitBE(header_offset+0xf6+i*2,streamFile);
diff --git a/src/meta/excitebots.c b/src/meta/excitebots.c
index 5ba06f00..2f5de05b 100644
--- a/src/meta/excitebots.c
+++ b/src/meta/excitebots.c
@@ -82,6 +82,7 @@ VGMSTREAM * init_vgmstream_eb_sfx(STREAMFILE *streamFile) {
 
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_EB_SFX;
+    vgmstream->allow_dual_stereo = 1;
 
     /* open the file for reading */
     {
diff --git a/src/meta/genh.c b/src/meta/genh.c
index 70cac106..22a39025 100644
--- a/src/meta/genh.c
+++ b/src/meta/genh.c
@@ -325,6 +325,7 @@ VGMSTREAM * init_vgmstream_genh(STREAMFILE *streamFile) {
 
     vgmstream->coding_type = coding;
     vgmstream->meta_type = meta_GENH;
+    vgmstream->allow_dual_stereo = 1;
 
 
     if ( !vgmstream_open_stream(vgmstream,streamFile,genh.start_offset) )
diff --git a/src/meta/kraw.c b/src/meta/kraw.c
index 2fd4123e..a14a2146 100644
--- a/src/meta/kraw.c
+++ b/src/meta/kraw.c
@@ -37,6 +37,7 @@ VGMSTREAM * init_vgmstream_kraw(STREAMFILE *streamFile) {
 
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_KRAW;
+    vgmstream->allow_dual_stereo = 1;
 
     /* open the file for reading */
     {
diff --git a/src/meta/ngc_dsp_std.c b/src/meta/ngc_dsp_std.c
index 7908131a..b3ee0110 100644
--- a/src/meta/ngc_dsp_std.c
+++ b/src/meta/ngc_dsp_std.c
@@ -348,6 +348,7 @@ VGMSTREAM * init_vgmstream_ngc_dsp_std(STREAMFILE *streamFile) {
         vgmstream->loop_end_sample = vgmstream->num_samples;
 
     vgmstream->meta_type = meta_DSP_STD;
+    vgmstream->allow_dual_stereo = 1; /* very common in .dsp */
     vgmstream->coding_type = coding_NGC_DSP;
     vgmstream->layout_type = layout_none;
 
diff --git a/src/meta/ngc_dsp_ygo.c b/src/meta/ngc_dsp_ygo.c
index 77608018..e53905ef 100644
--- a/src/meta/ngc_dsp_ygo.c
+++ b/src/meta/ngc_dsp_ygo.c
@@ -39,6 +39,7 @@ VGMSTREAM * init_vgmstream_dsp_ygo(STREAMFILE *streamFile) {
     vgmstream->num_samples = read_32bitBE(0x20,streamFile);
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_DSP_YGO;
+    vgmstream->allow_dual_stereo = 1;
     if (loop_flag) {
         vgmstream->loop_start_sample = (read_32bitBE(0x30,streamFile)*14/16);
         vgmstream->loop_end_sample = (read_32bitBE(0x34,streamFile)*14/16);
diff --git a/src/meta/ngc_lps.c b/src/meta/ngc_lps.c
index 6957a782..bafa5f90 100644
--- a/src/meta/ngc_lps.c
+++ b/src/meta/ngc_lps.c
@@ -37,6 +37,7 @@ VGMSTREAM * init_vgmstream_ngc_lps(STREAMFILE *streamFile) {
 
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_NGC_LPS;
+    vgmstream->allow_dual_stereo = 1;
 
     if (vgmstream->coding_type == coding_NGC_DSP) {
         int i;
diff --git a/src/meta/ngca.c b/src/meta/ngca.c
index 271be64e..fb135204 100644
--- a/src/meta/ngca.c
+++ b/src/meta/ngca.c
@@ -34,6 +34,7 @@ VGMSTREAM * init_vgmstream_ngca(STREAMFILE *streamFile) {
 
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_NGCA;
+    vgmstream->allow_dual_stereo = 1;
 
 	 if (vgmstream->coding_type == coding_NGC_DSP) {
          int i;
diff --git a/src/meta/nub_vag.c b/src/meta/nub_vag.c
index c74393e9..6d68746c 100644
--- a/src/meta/nub_vag.c
+++ b/src/meta/nub_vag.c
@@ -32,6 +32,7 @@ VGMSTREAM * init_vgmstream_nub_vag(STREAMFILE *streamFile) {
 
     vgmstream->layout_type = layout_none;
     vgmstream->meta_type = meta_NUB_VAG;
+    vgmstream->allow_dual_stereo = 1;
 
     start_offset = 0xC0;
 
diff --git a/src/meta/ps2_smpl.c b/src/meta/ps2_smpl.c
index e44bd7ed..b4a03712 100644
--- a/src/meta/ps2_smpl.c
+++ b/src/meta/ps2_smpl.c
@@ -8,11 +8,11 @@ VGMSTREAM * init_vgmstream_ps2_smpl(STREAMFILE *streamFile) {
     int loop_flag, channel_count;
     size_t channel_size;
 
-    /* check extension (.v0: left channel, .v1: right channel, .smpl: header id) */
+    /* checks*/
+    /* .v0: left channel, .v1: right channel
+     * .smpl: header id */
     if ( !check_extensions(streamFile,"v0,v1,smpl") )
        goto fail;
-
-    /* check header */
     if (read_32bitBE(0x00,streamFile) != 0x534D504C) /* "SMPL" */
         goto fail;
 
@@ -31,13 +31,12 @@ VGMSTREAM * init_vgmstream_ps2_smpl(STREAMFILE *streamFile) {
     vgmstream->loop_end_sample = vgmstream->num_samples;
 
     vgmstream->meta_type = meta_PS2_SMPL;
+    vgmstream->allow_dual_stereo = 1;
     vgmstream->coding_type = coding_PSX;
     vgmstream->layout_type = layout_none;
 
-    /* always, but can be null or used as special string */
     read_string(vgmstream->stream_name,0x10+1, 0x20,streamFile);
 
-    /* open the file for reading */
     if ( !vgmstream_open_stream(vgmstream, streamFile, start_offset) )
         goto fail;
     return vgmstream;
diff --git a/src/meta/ps_headerless.c b/src/meta/ps_headerless.c
index e722e4d0..8a4a7d97 100644
--- a/src/meta/ps_headerless.c
+++ b/src/meta/ps_headerless.c
@@ -276,6 +276,7 @@ VGMSTREAM * init_vgmstream_ps_headerless(STREAMFILE *streamFile) {
     }
 
     vgmstream->meta_type = meta_PS_HEADERLESS;
+    vgmstream->allow_dual_stereo = 1;
 
     if (!vgmstream_open_stream(vgmstream,streamFile,start_offset))
         goto fail;
diff --git a/src/meta/rwsd.c b/src/meta/rwsd.c
index 769f2bbf..7dd87f08 100644
--- a/src/meta/rwsd.c
+++ b/src/meta/rwsd.c
@@ -280,10 +280,13 @@ VGMSTREAM * init_vgmstream_rwsd(STREAMFILE *streamFile) {
         vgmstream->meta_type = meta_RWAR;
     else if (rwav)
     {
-        if (big_endian)
+        if (big_endian) {
             vgmstream->meta_type = meta_RWAV;
-        else
+        }
+        else {
             vgmstream->meta_type = meta_CWAV;
+            vgmstream->allow_dual_stereo = 1; /* LEGO 3DS games */
+        }
     }
     else
         vgmstream->meta_type = meta_RWSD;
diff --git a/src/meta/spt_spd.c b/src/meta/spt_spd.c
index 749ef0f8..5535a74b 100644
--- a/src/meta/spt_spd.c
+++ b/src/meta/spt_spd.c
@@ -71,7 +71,8 @@ VGMSTREAM * init_vgmstream_spt_spd(STREAMFILE *streamFile) {
     }
 
     vgmstream->meta_type = meta_SPT_SPD;
-	
+    vgmstream->allow_dual_stereo = 1;
+
     /* open the file for reading */
     {
         for (i=0;i<channel_count;i++) {
diff --git a/src/meta/txth.c b/src/meta/txth.c
index b8b02d72..b2ca9fac 100644
--- a/src/meta/txth.c
+++ b/src/meta/txth.c
@@ -384,6 +384,7 @@ VGMSTREAM * init_vgmstream_txth(STREAMFILE *streamFile) {
 
     vgmstream->coding_type = coding;
     vgmstream->meta_type = meta_TXTH;
+    vgmstream->allow_dual_stereo = 1;
 
 
     if ( !vgmstream_open_stream(vgmstream,streamFile,txth.start_offset) )
diff --git a/src/meta/vag.c b/src/meta/vag.c
index 2e58441c..e88a78a5 100644
--- a/src/meta/vag.c
+++ b/src/meta/vag.c
@@ -11,7 +11,7 @@ VGMSTREAM * init_vgmstream_vag(STREAMFILE *streamFile) {
     int channel_count = 0, loop_flag, sample_rate;
     uint32_t vag_id, version;
     int32_t loop_start_sample = 0, loop_end_sample = 0;
-    //int allow_dual_stereo = 0;
+    int allow_dual_stereo = 0;
 
 
     /* checks */
@@ -195,7 +195,7 @@ VGMSTREAM * init_vgmstream_vag(STREAMFILE *streamFile) {
 
                 channel_count = 1;
                 loop_flag = ps_find_loop_offsets_full(streamFile, start_offset, channel_size*channel_count, channel_count, interleave, &loop_start_sample, &loop_end_sample);
-                //allow_dual_stereo = 1; /* often found with external L/R files */
+                allow_dual_stereo = 1; /* often found with external L/R files */
             }
             break;
 
@@ -209,6 +209,8 @@ VGMSTREAM * init_vgmstream_vag(STREAMFILE *streamFile) {
     if (!vgmstream) goto fail;
 
     vgmstream->meta_type = meta_type;
+    vgmstream->allow_dual_stereo = allow_dual_stereo;
+
     vgmstream->sample_rate = sample_rate;
     vgmstream->num_samples = ps_bytes_to_samples(channel_size,1);
     vgmstream->loop_start_sample = loop_start_sample;
diff --git a/src/vgmstream.c b/src/vgmstream.c
index f0f4e738..a691fc69 100644
--- a/src/vgmstream.c
+++ b/src/vgmstream.c
@@ -474,23 +474,7 @@ static VGMSTREAM * init_vgmstream_internal(STREAMFILE *streamFile) {
         }
 
         /* test if candidate for dual stereo */
-        if (vgmstream->channels == 1 && (
-                    (vgmstream->meta_type == meta_DSP_STD) ||
-                    (vgmstream->meta_type == meta_PS2_VAGp) ||
-                    (vgmstream->meta_type == meta_GENH) ||
-                    (vgmstream->meta_type == meta_TXTH) ||
-                    (vgmstream->meta_type == meta_KRAW) ||
-                    (vgmstream->meta_type == meta_PS_HEADERLESS) ||
-                    (vgmstream->meta_type == meta_NGC_LPS) ||
-                    (vgmstream->meta_type == meta_DSP_YGO) ||
-                    (vgmstream->meta_type == meta_DSP_AGSC) ||
-                    (vgmstream->meta_type == meta_PS2_SMPL) ||
-                    (vgmstream->meta_type == meta_NGCA) ||
-                    (vgmstream->meta_type == meta_NUB_VAG) ||
-                    (vgmstream->meta_type == meta_SPT_SPD) ||
-                    (vgmstream->meta_type == meta_EB_SFX) ||
-                    (vgmstream->meta_type == meta_CWAV)
-                    )) {
+        if (vgmstream->channels == 1 && vgmstream->allow_dual_stereo == 1) {
             try_dual_file_stereo(vgmstream, streamFile, init_vgmstream_functions[i]);
         }
 
diff --git a/src/vgmstream.h b/src/vgmstream.h
index b6f63345..1366371b 100644
--- a/src/vgmstream.h
+++ b/src/vgmstream.h
@@ -757,10 +757,11 @@ typedef struct {
     int num_streams;            /* for multi-stream formats (0=not set/one stream, 1=one stream) */
     int stream_index;           /* selected stream (also 1-based) */
     char stream_name[STREAM_NAME_SIZE]; /* name of the current stream (info), if the file stores it and it's filled */
-    size_t stream_size;         /* info to properly calculate bitrate */
+    size_t stream_size;         /* info to properly calculate bitrate in case of subsongs */
     uint32_t channel_mask;      /* to silence crossfading subsongs/layers */
     int channel_mappings_on;    /* channel mappings are active */
     int channel_mappings[32];   /* swap channel "i" with "[i]" */
+    int allow_dual_stereo;      /* search for dual stereo (file_L.ext + file_R.ext = single stereo file) */
 
     /* looping */
     int loop_flag;              /* is this stream looped? */
@@ -804,7 +805,7 @@ typedef struct {
 
     int32_t ws_output_size;         /* WS ADPCM: output bytes for this block */
 
-    void * start_vgmstream;         /* a copy of the VGMSTREAM as it was at the beginning of the stream (for AAX/AIX/SCD) */
+    void * start_vgmstream;         /* a copy of the VGMSTREAM as it was at the beginning of the stream (for custom layouts) */
 
     /* Data the codec needs for the whole stream. This is for codecs too
      * different from vgmstream's structure to be reasonably shoehorned into
@@ -812,9 +813,7 @@ typedef struct {
      * Note also that support must be added for resetting, looping and
      * closing for every codec that uses this, as it will not be handled. */
     void * codec_data;
-    /* Same, for special layouts.
-     * Reusing the above pointer causes bugs when it's using special layout + codec
-     * (vgmstream may try to free/loop/etc codec_data). */
+    /* Same, for special layouts. layout_data + codec_data may exist at the same time. */
     void * layout_data;
 } VGMSTREAM;