Major Description
If the retrieve job maps different artifacts of the same module to the same filename, Ivy should throw an error.
This would solve problems when retrieving artifacts from the maven repositories where also sources/javadocs artifacts exists and where the retrieve pattern doesn't distinguish between them (doesn't contain a [type] or [classifier] token). At the moment, a random selected artifact is being retrieved, which results in unpredictable builds...
The behaviour when multiple artifacts of different modules are mapped to the same file should remain as is to keep backwards compatibility as much as possible: a conflictmanager selects the most recent artifact.