You might notice at times that the bid/max bid and the current bid shows the same number, but you are outbid even though the current bid is same as your bid.
This is because someone had placed a max bid amount. The maximum bid (max bid) amount placed by the other bidder was the the bid that you placed. Your bid prompted the bidding system to raise the other buyer's max bid. This earlier bid would be the valid bid (since that bidder had placed their max bid hours or days before)
Saying this another way, if YOU place a max bid amount, and someone else comes along and places a bid identical to your max bid, their bid would prompt the bidding system to raise the max bid. Your bid would be the valid bid (since you had placed a max bid hours or days before the next bidder).