LOL...yep!

Apparently it really can happen! From a google search:

She does not come into heat again while she is still in heat, but she can conceive each time she breeds during that heat. A cat's biological make up lets them produce eggs for fertilization each time she breeds so she can have several fathers for her litter.

It's not good to let her keep breeding though as the last kittens conceived could be up to a week younger in gestation than the first conceived. She will only have one labour and delivery however many times she breeds. The last kittens maybe too immature at birth to survive. If they do you may have to hand raise them as they may not be strong enough to nurse from the queen.

I had a cat once who two kittens, one pure black, the other pure white like the mom. There were no black cats around, so we had no idea if they came as a pair from one tom or two!