You may want to study [1] - this is the latest thinking on agent collaboration from Google.
[1] https://www.linkedin.com/posts/shubhamsaboo_we-just-ran-the-...
Autogen from ms was an early attempt at this, and it was fun to play with it, but too early (the models themselves kinda crapped out after a few convos). This would work much better today with how long agents can stay on track.
There was also a finding earlier this year, I believe from the swe-bench guys (or hf?), where they saw better scores with alternating between gpt5/sonnet4 after each call during an execution flow. The scores of alternating between them were higher than any of them individually. Found that interesting at the time.
I don’t know if benchmarks, sorry.