You could try to use your ClassLoader, instead of System one - but at this case you need to write your utility for getting resource bundle (you could check timestamp, to deside, does it need to be reloaded).
It kind of funny, but when you say that package/class name should be uniq,
you should add - within same classloader.
You could have a simple code, wich will allow you to have two different version of same class in the system
