A friend of mine had some explaining to do when he screwed up a dhcp config change and started routing his guest wifi through his "personal" pihole instead of the restricted guest one (he had family/children over often and did not want to be the reason nephew Timmy got an eyeful of wet bush or a beheading).
His family-friendly pihole was at holypi.lastname.local and his private one was creampi.lastname.local