Hey there!
Yes a bee can sting a bee. I am not sure if it dies though.
When a bee stings thick skinned animals such as humans, it quickly tries to get away therefore ripping the stinger out and killing it. When a bee stings another insect, the stinger is not as easily ripped out therefore the bee will live, I am not sure if the bee in which was stung would survive though.
I hope this helped! :-)