There was the Indiana-Michigan game this year where the ruled it an interception when it was a simultaneous catch. The tie goes to the offense. If the teams would have been reversed, I don't believe that would have been called an interception.
I don't like the excessive celebration penalty, it's used far too subjectively. OK, a flip going into the end zone, that's not spontaneous, that's just someone trying to make a highlight reel. But spontaneous brief bursts of excitement run the risk of getting flagged if the ref feels like it.