If 2 objects on 2 different DCs end up with the same DN, then when the DCs replicate with each other, they should resolve this conflict by renaming one of the objects. Currently, Samba may rename a different object compared to Microsoft.
If the RMD_VERSION for the objects (name attribute) differs, then Samba will pick the object with the highest RMD_VERSION. Currently Microsoft seems to ignore RMD_VERSION and just uses the time-stamp and GUID to resolve the conflict.
This could cause problems in a mixed network with both Samba and Microsoft DCs. I haven't tested it, but presumably the conflicting DN would end up using a different GUID on the Microsoft DC compared to the Samba DC.
Windows behaviour seems to match their current spec (126.96.36.199.12 ResolveNameConflict).
Note if working on this bug: If possible, it might be worth testing the behaviour when the timestamps are identical. From the Docs, it looks like Microsoft may use the object GUID whereas Samba uses the DC GUID (originating_invocation_id).