I'm seeing two accounts if you search for jack@primal.net, I'll edit and link though. 
Discussion
That’s weird cause it’s not possible for 2 people to have the same nip-05. What client is that?
The Nostr Address isn't validating for them, as the hex pubkey is not correct. NIP-05 should also be handled as case-insensitive. So both `Jack` and `jack` and `JACK` will all be valid for the same pubkey. Which appears to be the case if you use any of those with this https://primal.net/.well-known/nostr.json?name=jack it shows the same pubkey. That doesn't stop someone from adding it as their Nostr Address, but it won't validate.
that seems like a bug in the nostr client. it shouldn't display the accounts with invalid nip-05s when searching by nip-05.
Primal
That’s funny cause it’s a primal nip-05 😂
weird no users show up when i search that jack@primal.net in primal. i just checked jack's kind 0 and he doesn't even have a nip-05 set up on his profile. jack@primal.net is his lightning address though.