The code for detecting network overlaps in NAPI is currently a bit racy. I expect this to get worse with NAPI-434, which could result in multiple requests all working their way along trying to create the same several networks.
To protect against two overlapping networks accidentally being created, I'd like to move the overlap code into a Moray pre-trigger on the napi_networks bucket, so that we can work from inside the transaction, and make sure that it's safe to create the network.