WHAT, They Did A Duet?

Britney spears has done a duet with Heidi Montag! WHY??????

We dont know why-Britney is more crazier than we thought we guess!

Here are the details thanks to Perez Hilton, "Well, all is not always as it seems, especially when the "reality" stars of The Hills are involved!

Yes, both stars appear on a new track, but Britney did not authorize the song's release and she had no idea about it until Montag leaked it, sources tell us.

"Heidi and Spencer got their hands on an old demo recording of Britney's that never made it onto any of her albums," an insider reveals exclusively to PerezHilton.com. "They've been working with a lot of producers on Heidi's new album and one of them gave them the track. They decided to turn it into a duet instead of having Heidi re-record the song with just her vocals because they knew they'd get more press this way."

We say, thats shady! Heidi knew her album SUCKS and would get ZERO sales or airplay! Britney should sue...or kick her ass.

Click HERE! To check it out.