This error happens if the specified personal or file geodatabase being checked out to already has an existing checkout/check-in replica. Both personal and file geodatabases have this limitation. ArcSDE geodatabases do not. ArcSDE geodatabases can support multiple checkout/check-in replicas.
To resolve this issue, specify a file or personal geodatabase that does not have an existing checkout/check-in replica. You can use the replica manager to view existing replicas in a workspace.