My first thought is what almut wrote already. Probably what happened is that you dumped HTTP::Connection=HASH(0xbef7360), it was then destroyed, and the memory was reused to make HTTP::OtherClass=HASH(0xbef7360) (so it has the same address).

It's also possible to bless an existing object into some other class. In that case, rather than HTTP::Connection=HASH(0xbef7360) being destroyed, it just got reblessed into HTTP::OtherClass somewhere.

Either way, you wouldn't see HTTP::Connection=HASH(0xbef7360) and HTTP::OtherClass=HASH(0xbef7360) at the same time, only in two separate dumps.