I don't really understand what you are trying to do?
The LAST policy is certainly non-deterministic since it means the
used version of a package could change at random based on what gets deployed when.
That would break all the consistency checking.
The idea of split packages is that two modules can provide the same exported package
but only if they are at the same version. The importing module should then import BOTH
(in some deterministic order - e.g. first deployed is the first to be used).
The validation of the ClassLoaderSpace should not treat this as an error (which it currently does).