that solves the problem of "stomping on things" in the short term but it might not be trivial to merge these later. depending on what kind of tasks you're giving them and the style in which they do them it could be anything from "no problems" to "lots of headaches" -- the same is true for human developers.
(I've definitely seen 20 developer teams that were spinning their wheels because they were stomping on each other despite using version control as well as teams that had code rot because they had a "no refactoring/don't touch a file you can possible avoid touching" policy)
I agree. However as you said, you can consider code agents like human contributors. My feedback is that an army of Claude Code instances with a strict CLAUDE.md file is more rigorous than a human team.
(I've definitely seen 20 developer teams that were spinning their wheels because they were stomping on each other despite using version control as well as teams that had code rot because they had a "no refactoring/don't touch a file you can possible avoid touching" policy)