I'm assuming your talking about which resource (class, properties, etc...) will get loaded?
1.) They may be loaded by different class loaders, in which case it is usually the highest ancestor class loader that wins. Unless the jars gets loaded as part of a webapp (in
servlet 2.4 spec and above) then, usually, it is the webapp classloader.
2.) If it is the same classloader then I don't believe there to be a specified behavior. OTOH, if the files are listed in an environment or command line classpath I've yet to see a case where they are not loaded in the listed order.
Where are the jars? a webapp, on the classpath, in lib/ext, in an ear file, referred to in a manifest, etc ...?