I have now solwed my problem.
I have named my .properties files so that they are unique within the .ear file.
But my question still remains. Is it not allowed to have files that are named exactly the same if they are placed in different .jar files within one .ear file?
The classloading in 3.0.5 has been changed so
that all sub-deployments (ejbs) of a top level
deployment (ear) share the same classloader.
Before, each jar got its own classloader.
This fixes problems where classes in supporting
libraries make package private access to each other.
But it does mean you cannot uniquely load resources
from a sub-deployments jar, as you have found.
This "new" behaviour was also the behaviour in JBoss2.x
If you are not happy, report it as a bug