If don't need that level of synchronization then I would keep the robots separate. It is much simpler to have separate robot controllers and programs.
if you can solve the task with several robots(controllers) with just a few handshakes: buy several robots(controllers).
This is always easier to program: multi tasking debugging and monitoring is always ( on the pc as well as with robots around powers more stupidly and/or more annoying!
Multiple TPs is also always(!) better.