Yes, I have 2 links for MediaMonkey on the desktop, one for MM4 and one for MM5.
MM4: Target: "D:\MediaMonkey 4\MediaMonkey\MediaMonkey.exe"; Execute in: "D:\MediaMonkey 4\MediaMonkey"
MM5: Target: "D:\MediaMonkey 5\MediaMonkey.exe"; Execute in: "D:\MediaMonkey 5"
I don't see anything special here. Maybe that MM4 portable is installed in a "MediaMonkey 4" subfolder while MM5 portable is directly in D:
Added later: I found that in D:\MediaMonkey 4\MediaMonkey\Portable I have an old MM5.DB (from July 2020) in addition to MM.DB. Not sure where this comes from, probably from myself saving the DB in the wrong place

. I can try to delete it and see if the installation runs through this time if you like.