I haven't tried personally (haven't the need, I was conveying Jim Heid's experience) but I think it is very likely. After all I've successfully used two different versions of Acquisition simultaneously (just d/l'ing back ups of tunes I already own of course ).
The standard is that the most recent version of the app runs "over top" of the previous ones but if you want the features of the previous one you can use it. For example, QT stopped letting you edit and save around version 4. If you installed and opened QT2..5, you would have the best of both worlds - the new features and the ability to edit and save. Doesn't seem to work in the new version of QT though, I may have to buy the pro version or run an extensions setting without the QTplugin and straight download.