That's trick, I had used it once and won auction.
It goes like this:
You want to buy 2 players, first one costs 80M, second one costs 90M, your budget is 100M.
Auctions: 1. 15:00 to end
2. 30:00 to end
Bid 1T for both players before 1st auction ends!
You have won 1st auction and now your budget is 20M, but your offer for second player is still active.
Don't know why, but when knock-out rounds start, sometimes you will and sometimes won't be able to bid.
I have tried that few times, now my club has money so I dont have to do it.