If there are OSPF routers with the same router ID in a topology, then OSPF will simply not function correctly. OSPF routers with the same ID will not become neighbors, but you can still have duplicate router IDs in an active OSPF topology. Such a situation can have unpredictable results. There is no “normal” behaviour in such a situation, so any strange behaviour that you observed cannot really be evaluated as a bug.
You can find out more about the router ID and the consequences of it not being unique in a topology at the following lesson:
I hope this has been helpful!