MAVlink Packet routing issue with more then one link and GCS

For redundancy out plane has a Groundstation SYSID 254 on a radiolink on SERIAL1
and another GCS, let’s call it SYSID 252 on another radiolink on SERIAL2
(the radiolinks are completely different, only one is based on 3DR HM-TRP modules)

On each GCS, we can see the other GCS’s heartbeat and terrain and some other packets.
Apparently those are routed via the Pixhawk.

in case MissionPlanner or MAVproxy, the SiK telemetry stats go nuts when heartbeats from both GCS’s arrive (I guess the sequence numbers make it detect out-of-sequence / dropped packets)

Also other mavlink interfaces, like SERIAL3 - will suddenly start to send the secondary GCS’s heartbeats.

Is there a way of preventing routing of both GCS’s between interfaces on the ArduPilot?