Thanks for your thoughts!
I think I was not clear enough about the used directory structure.
The application is a single pure Perl script (not implemented as a module) delivered as an entire tree of files including non-system modules being used.
The application is used as a "local" installation (not under "Program Files", but in it's own bin directory with needed modules supplied also locally in sub directories). It is a bundled set residing in one directory.
The Perl installation OTOH is globally (standard installation from msi installer).
The question is if I could merge 32 and 64 variants of needed modules locally together, to be 32/64-Bit agnostic.