This will create a new folder and not update the previous binary. Shouldn't us notifícate the user in some way or remove the /Pivx folder automatically?

The old uninstaller should remove the binary from the old folder.

the old uninstaller will certainly remove the old binary and installation dir...however, the running of the old uninstaller would need to be done manually prior to running the new installer with this change as-is.

I believe there is a way to script the running of an old/existing uninstaller prior to continuing with a new install, but haven't really looked into it.