Who wins when both teams score above 500 in Double Deck Pinochle?
There are many different sets of rules for Pinochle, most are the same but almost every household I've played at has something 'different'.   

However, my understanding of the winner (in what ever variation being played) was the one who won the bid will be the winner regardless of the scores if both are winning scores.  This is because it forces each bidder/team to make a serious attempt at the final bid.  The one who wins the bid is putting their money where their mouth is so to speak.  If I win the bid and just make the min score, and you only needed 1 point so you are much farther ahead, you could take it easy and assume a win and not bother trying to bid your hand.