Airprint printing to identical printer on a different network

Hello,

I recently setup an Epson WorkForce WF3520 printer to my parents wifi network.

They can print to it from all of their devices just fine, however the people next door have the exact same printer and last night the print out's appeared on their printer next door, even though our network is password protected and our printer is connected to our network only.

I am thinking that when my father was printing from his iPad to his printer, Airprint has somehow picked up the printer next door, on a different network and printed to it?

How can I fix this. Personal items ending up on next door's printer is not ideal.

Thanks in advance