I don't get this ... Why is it the broker's responsibility to make sure the publishers are not duplicating ? Rather than fixing the code and fix the root cause ?
With this feature, the producer still needs to implement a strictly increasing sequence value, make sure its state is persisted, and use that as the publishing ID.
What if you need to restore your DB after a crash, and need to reprocess data to catch up ? If you stored your publishing ID sequence in that DB, your "smart" broker will happily drop these messages ... !?
Unless there's something I don't understand, that sounds like a really bad "good idea".