Yes, but a user would need to be experienced enough to know how to uninstall the previous desktop environment components they don’t want, otherwise their application menu would have both DE’s applications (2 file managers, photo viewer’s, text editors, terminals, etc), which can feel a little cluttered.

Yeah, you can install both, then just pick which one you want during login.

https://forums.linuxmint.com/viewtopic.php?t=214635