You can find your answer here >>>https://forum.onlinesoccermanager.com/topic/302/common-questions/13
Since your scout brought Messi twice and you didn't sign him he assumed you don't want that player so he brings someone else who fits your preference. To avoid this in case of next time don't open your scout unless you have enough money to sign the players you sent the scout for.
You can adjust your preferences to see if it helps you bring other 90+ players.
You can use both methods (checking the transfer history or each team in the league)