Description
This error can occur during replica creation (using either the Create Replica or Create Replica From Server tool) if the Replica Name parameter conflicts with a replica name that exists in either the source or destination geodatabase. Each replica name must be unique to the user creating it. User1 and user2 could each create a replica called MyReplica, but neither could create multiple replicas with that name.
Solution
Change the value of the Replica Name parameter so that it doesn't conflict with an existing replica owned by the connected user.