In a distributed development environment (a central server with the 'good' set of source), when you use Replication to Pull a branch you can identify the source repository in the before-replicationwrite trigger from the PLASTICREPLICATIONSOURCE environment variable and the target repository from the PLASTICBRANCH environment variable. In this way you can check that the repositories match and you aren't corrupting your local repository with branches from another repository.
However, when you Push a branch, there is no way for the before -replicationread trigger to check you aren't corrupting the central repository by matching you local repository name with your target (central) repository.
Could you add PLASTICREPLICATION_TARGET with the repository on the target server?