How can a transmission be in park and in gear at the same time?

Setting on a hill and reved up engine when I heard a pop, after this
I no longer had park. It bent the parking pawl. Has anyone ever heard
of this happening before.........

 

Sounds like there is something wrong with the valve body.

 

Thanks for the reply
I have had the parking pawl repaired, but they did not say they corrected anythingelse could this happen again if it is a valve body problem.