Scripting_Ace suggested to rename the apps. Reveal their contents in the Finder (mind quitting the apps as well as your script editor) and edit Info.plist file by changing the CFBundleName to say QuarkXPress6.52 and QuarkXPress7.5. Reboot your Mac.
HTH.
Jean-Marie Schwartz
> Mac Pro Quad Core Intel 2.8 GHz, OS X.6.8, Quark XPress 9.2, Adobe CS5 <