Chris BurtonI have no idea why you'd want to do it but whilst fixing a @DNSHistory stats issue I spotted ~4500 domains have multiple (duplicated) SOA records.
For example https://dig.domains/soa/mrmmobilya.com has 7 SOA records (via Google Public DNS). Quad9 only returns one but Cloudflare, OpenDNS, and a local PowerDNS Recursor also return 7.