Generally speaking, if you want to install one of the "bigger" mods like Camarilla Edition, The Final Nights or Clan Quest Mod, you should not install them over the Unofficial Patch or any other mod (most of them include their own version of the UP and build upon it). This can and most likely will break stuff, cause glitches/bugs, and make the game unplayable (not to mention your saved games might not work anymore). It's not guaranteed that stuff breaks, but it's highly likely. Doing it the way Thiev described above by creating a separate folder and changing the shortcut is the safe way to do it.