He didn't really intend to bid against himself, he placed an "insurance" bid.....in case of last-second snipe bids higher than his $1800.01.

We don't know what his last bid actually was (it could have been anything from $1825 on up) the proxy bid amount is all that will show on the bidding history. (The bid could have been $3000, for all we know.)

The reason $1825 showed is because that was the next increment for the proxy bid (previous bidder was at $1800).

Had he not placed the last bid (that shows as $1825) he would have won he auction for $1800.01, which was the highest bid, to that point.

I don't know if this explanation will make things clearer or muddier!!