I actually spent the past few days testing this out, and I've figured out how Chainsaws work, on a technical level. Essentially, to prevent Duct Taped Cleavers from infinitely proccing each other, each Cleaver can be used multiple times per round, but is only actually allowed to activate each other Cleaver once in a given round. That means that if Cleaver A activates Cleaver B at its side, then Cleaver A can't also activate Cleaver B through Duct Tape.