As I see it we have a few alternative interpretations.
1. The Backdoor is real.
Signals sent from P&H may have included a backdoor command code that was built into the programming that even Jose, Dylin and her crew did not know about. P&H may be using it to send instructions to the probes with which they are compelled to comply or questions they must answer.
2. The Beanie has learned how to talk to them.
The Beanie may have been analyzing their chatter between themselves and the other probes. They may have devised a means of talking to Andrew and Enoch (and, by extrapolation, to any of the probes) and are testing it by making innocuous queries that would not raise any alarms with them or us.
They may not have recognized that our transmissions are coming from Earth. If they had, they might have tried to insert messages into our comm system (it would be very easy for them to mimick a new poster if they could figure out how to get the transmission into the system in the first place).
Even if they do know we are not on Mars, they may not be concerned about us nor the fact that we can deduce they are "hacking" into our communications with the probes. They may not care that we can hear the responses to their queries.
3. The ETs have taken Bette's transciever and are talking.
The ETs may have recognized they need to make contact with the probes, especially after discovering they now have drones to use as additional forces. The sample of metal from the drone has probably been analyzed and compared to metal from Bette. It is very likely they are the same or sufficiently similar for the ETs to conclude they have common origins. The ETs may be trying to establish contact and are using a cautious approach of minimal transmissions with inconsequential content until they are certain they cannot be harmed by the communications equipment.
Koala, Captain, Team Andrew