How to beat team with double LeftWingers?

[Tactician]

How is the quality of your team compared to your opponent?

If you have a very good defense, 3W-5-2 can be used with passing: mixed, focus passing: right flank. If your defense is weak or average, 4-4-2 classic can be used as 4 at back is more safe. 3W-1-4-2 could also work.
4-3-3 may work if you use long passing and focus through the middle.
It depends on the difference in quality of both teams and what orders the opponent plans to use. The mentality you choose is also important. Usually, a defensive mentality is advised against much stronger opponents and an attacking mentality is advised against much weaker opponents.

So, I recommend you to start with 4-4-2 with focus passing (mixed) on the flank opposite to flank where there are 3 players. Use the same mentality that you used for the previous match that you won 1-0 against him. See how the game goes by following the statistics and the comments, and make appropriate changes if required. Also, if you don't really need to beat this team to win a competition or move a place above in the league for Champions League qualification, then no need to take risks as a draw would be a decent result.

Try to follow the game though as it seems that he has a tendency to put an extra player on either wing. If he makes a change and put the 'extra' player on the other flank, then switch your passing focus to the opposite flank (unless your team is using 4-3-3).

Come back to tell us the result.