Why does Lichess allow a player to play two games at the same time?

A player that I faced stop playing me midway the game and was already playing another before the time run out in the game with me.

This shouldn't be allowed and happened to me two times in the last 3 days.

These persons neither abandon the game (by closing the tab) nor resign. They just start another game.

And another one! Seriously! WTF!!