I'm no expert on this, but if 2 of the same particle-generators seem to rule each other out (like they're "playing" in sync), then maybe it's an idea to try to let them run "out of sync"?
Like - suppose the part.generators work in cycles/ms - the left generator emits at 1ms/3ms/5ms etc, while the right generator emits at 2ms/4ms/6ms etc.
That way, when one generator is working, the other isn't, and vice versa.
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