https://bugs.winehq.org/show_bug.cgi?id=57857
--- Comment #3 from Alexandre Julliard julliard@winehq.org --- The goal is to make it possible to switch dynamically between old and new wow64 mode, and that can't work with separate libdirs.
Separate libdirs could be made to work by adding a couple of symlinks in the right places, but I don't think it's something we'd want to support.