There is only a 1 in 100,000 chance of another user, bidding on the same item as you.  We have never had two accounts enter the exact same Max Bid on the same item.  While we do not see this happen often, if it does, here is how the winner is determined:

1. Always remember, the highest bid wins!
2. If 2 bidders bid the exact same amount (both a sniper or manual bid), the earliest bid wins.  This is the only time sniping, has a bad outcome.

To ensure the best chance of winning, make sure you enter your TRUE Max Bid (the most you are willing to spend on the item), don't bid in increments of 5s or 10s and don't bid even amounts (example: 31.57 instead of 31.00).