I get the same signatures for quantum depth 8 as in
http://trac.imagemagick.org/browser/ImageMagick/branches/ImageMagick-6.5.8/PerlMagick/t/montage.t
http://trac.imagemagick.org/browser/ImageMagick/branches/ImageMagick-6.5.8/PerlMagick/t/write.t
in these four tests. For quantum depth 16, the signatures are correct.
Index: ImageMagick-6.8.4-0/PerlMagick/t/montage.t
===================================================================
--- ImageMagick-6.8.4-0.orig/PerlMagick/t/montage.t
+++ ImageMagick-6.8.4-0/PerlMagick/t/montage.t
@@ -153,7 +153,7 @@ testMontage( q/bordercolor=>'blue', matt
 testMontage( q/bordercolor=>'blue', mattecolor=>'red'/, 
   q/background=>'#696e7e',, tile=>'4x4', geometry=>'90x80+6+6>', frame=>'8x10',
   borderwidth=>'0', gravity=>'Center', shadow=>'True',background=>'gray'/,
-  '61645a8c80a7220a4260133a2b1ae720bf2755f2ed880a3fef0e9453641f5b79',
+  'd4de864f9004b185297c9c2351f811aaeb779095bdd8fd5f29bcfbee79f09da4',
   'bcd96dabb454c5d25091422763b1cdecb6a69a9b02b84a5b7fa0a70f150b957c',
   '079a08058fa670d60be858828a42732a2a6e1a4c34f2d179661b0fb71f719219');
 
@@ -164,7 +164,7 @@ testMontage( q/bordercolor=>'blue', matt
 testMontage( q/bordercolor=>'blue', mattecolor=>'red'/, 
   q/background=>'#696e7e',, tile=>'4x4', geometry=>'90x80+6+6>', frame=>'8x10',
   borderwidth=>'0', gravity=>'Center', shadow=>'True', texture=>'granite:'/,
-  '4655b59218afbd58d24a9ecf162a42868b3de40ecc8e9f9671dccf8b17e1aa33',
+  '8418407b6d56d2c1b67bc735004794d9eb20609d30115a93255eefcad3499e95',
   '9209b2db884fa4730eeab6c410b90e094fa305635baab7ede17270c13f6e80ad',
   '877a7277907a804286062823461c37690edaaa5d0bc7b813989bcaa0d4ebeaaf');
 
Index: ImageMagick-6.8.4-0/PerlMagick/t/write.t
===================================================================
--- ImageMagick-6.8.4-0.orig/PerlMagick/t/write.t
+++ ImageMagick-6.8.4-0/PerlMagick/t/write.t
@@ -72,14 +72,14 @@ print("CompuServe graphics interchange f
 testReadWrite( 'GIF:input.gif',
   'GIF:output.gif',
   q//,
-  '0c2e3c82fd375360fba16258bfa83e35b8c878fd208da9818b50e423426cc437');
+  '5a25065144213cd0230b7572bd9aef0e447c23a0622193a94ae62c9895c44bf7');
 
 print("CompuServe graphics interchange format (1987) ...\n");
 ++$test;
 testReadWrite( 'GIF87:input.gif87',
   'GIF87:output.gif87',
   q//,
-  'b68fe02737630f219fbf1f9ef3f24cf2b73c21848443a02df2cc2c0212a65657');
+  '0138e1e5c9a7ed1604ec5bbe8c22378b84fcd9abb8c36e984b051f9efc14d54e');
 
 print("Magick image file format ...\n");
 ++$test;