I used to have different Perl versions between Cygwin and MS Windows. Cygwin was at Perl 5.8 and Windows was at 5.10.1.

Along the way, I hit some button that upgraded Cygwin and the result appears to be that both are at Perl 5.10.1

I don't know how to explicitly maintain different versions.
The Cygwin upgrade apparently figured out that I had a more recent Perl and it used it. How and why? I don't know. But that appears to be what happened.

C:\Projects>perl -V
Set up gcc environment - 3.4.5 (mingw-vista special r3)
Summary of my perl5 (revision 5 version 10 subversion 1) configuration
+:
....
  Locally applied patches:
        ActivePerl Build 1007 [291969]
        0abd0d disable non-unicode case insensitive trie matching
  Built under MSWin32
  Compiled at Jan 26 2010 23:15:11
  @INC:
    C:/Perl/site/lib
    C:/Perl/lib
    .

C:\Projects>bash
bash-3.2$ perl -V
Set up gcc environment - 3.4.5 (mingw-vista special r3)
Summary of my perl5 (revision 5 version 10 subversion 1) configuration
+:
....
  Locally applied patches:
        ActivePerl Build 1007 [291969]
        0abd0d disable non-unicode case insensitive trie matching
  Built under MSWin32
  Compiled at Jan 26 2010 23:15:11
  @INC:
    C:/Perl/site/lib
    C:/Perl/lib
    .
bash-3.2$
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