My RODC is replicating changes to the Writeable DC

I have a domain with two DCs, one (Server01) is a writeable DC, and the other (Server02) is an RODC. The strange thing is that when I create a user or group, or change group membership on Server02, its replicated to Server01. I only have one site.
Isn't replication supposed to be just from Server01 to Server02, and not from Server02 to Server01, since 02 is and RODC? 02 was installed using a prestaged account.
What could be causing this? There is no replication connection for Server02 in Server01s NTDS Settings in AD Sites and Services. While there is RODC Connection (FRS) for Server01 in Server02s NTDS Settings.
Isn't replication supposed to be just from Server01 to Server02, and not from Server02 to Server01, since 02 is and RODC? 02 was installed using a prestaged account.
What could be causing this? There is no replication connection for Server02 in Server01s NTDS Settings in AD Sites and Services. While there is RODC Connection (FRS) for Server01 in Server02s NTDS Settings.
Current certs: MCP (210) MCSA (270, 290, 291 and 680) MCTS (680, 640)
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