Is it possible to have multiple installations of eJukebox in single machine (each in its own directory)? I tried it and it seems to work, but are there any hidden caveats?

This way, for example, in a computer shared by father, mother and kids, each user could see only his/her own cd collection.

Of course, it would be even better if you could install eJukebox just once, but have multiple user profiles and choose one of them when starting (e.g. ejukebox -user:father or something similar).

I also have been doing this for a long time (and for the same reason) and have not discovered any problems.

So yes: You can do it!