My impression (from well off to the side in a tangentially related field, mind you) has been that false positives are common enough in the individual detectors that they really do need the comparison with the other location&#x27;s data as a filter. (Not common enough for an actual coincidence to be at all likely, though.) I&#x27;m happy to be corrected if I&#x27;m wrong, of course! But I think the system has only been designed to be reliable as a whole.