Multiple domains pointed to the same IP

[Vijay]

I understand that there can only be one entry in the PTR file which gives
one domain name for a given IP address when a reverse lookup is performed.

Does this mean you cannot have mutiple domains map to a single IP on the
Internet e.g.:

one.mydomain.com    -> 192.1.2.3
one.anotherdomain.com -> 192.1.2.3

Thanks

Vijay