No, there's not a rule against buying the song multiple times. But opening several different iTunes accounts and buying them from different accounts is cheating. It shows insecurity. But hey, whatever floats your boat. Not my place to judge.
I brought HIAM from different accounts Don't hold it against me! I'll do the same for BTW
What did Katy Perry say? Everyone is hyper ventilating about it on twitter.
She said something like "Some people say they'd rather die onstage but that's just not me".
She deserves to be just on Radio Disney... not on the charts, where all the professionals are.