Can a decker with two cyberdecks and two unique agent programs load one agent onto each deck, slave one deck to the other, run their persona on the master deck and end up receiving teamwork tests from each unique agent?
Answer: Probably not, but the source is unclear, ask your GM.
This is a pretty tough question, and an excellent one! As a GM, I would have to rule that the agent is not sophisticated enough to assist in a teamwork test. I looked first to see if there were rules about if a deck can be slaved to another deck, and of course found nothing. According to the 5e Core Rulebook:
An agent is about as smart as a pilot program of the same rating (Pilot Programs, p. 269).
That bit says:
Pilots (the programs, not the people) are not bright. They’re called “dog-brains” by those who have to work with them, much the same way a particularly thick person might be called a “drone-head” by those who work with him.
When faced with something novel or unexpected, or a complicated command, a Pilot program must make a Device Rating x 2 Test against a threshold set by the gamemaster based on how confusing the situation is.
As a GM, I would rule it can if the task is simple enough to explain. The question then comes up if the agent can handle the task without you being jacked in through the deck its on and explaining it while it's doing it. Perhaps you can explain and have it perform each time? But I don't see that happening. I would have to rule that it couldn't, but because the source is unclear that would need to be left up to the GM. There's a very strong case for why it could work, but for me there's an even stronger case of why it wouldn't.