What jars are you overwriting in your Maven repo? The SNAPSHOT system allows things to be written in at the same time as other jobs depending on the previous version.
Is this a problem with SNAPSHOT jars or non SNAPSHOT jars? It looks like you're saying non SNAPSHOT: org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar being your example. Why do you need to publish that more than once ever? - Paul