Wil: Er, sorry, I'm not particularly inspired to ode you.
Bar Owner: I'll add five dollars to your paycheck for every five-dollar adjective you use.
Well she is now, of course, but Penelope Gaines was actually the original PG, long before we met Marten and Pintsize. But she was never the girl we know as Penelope, who is in fact a depowered clone of the original PG; created after an accident with a radioactive pizza oven and a lump of Calzonite left PG's uniform fused to her skin and impossible to remove, making her secret identity impossible to maintain. Our Penelope was decanted with a full set of memories of the civilian life of PG and so she truly believes she is Penelope Gaines and has no idea that she has anything to do with Pizza Girl, beyond a vague resemblance. Of course, since the original PG was killed and Hannelore took over, she really is just Penelope.
Hmm... putting this all together, perhaps Sara left Coffee of Doom to become Pizza Girl, then as Pizza Girl was eaten by an allosaurus. A new Pizza Girl took over in her place, whose clone became Penelope Gaines. The new Pizza Girl was killed, and then Hannelore took over. Eventually, Hannelore will be killed by her clone, and then another blonde girl will take over as Pizza Girl (perhaps Dora will stop dyeing her hair again and take over), thus continuing the line of succession of Pizza Girl.