1. He is a double dealer. I can't trust him.2. She sides with both her friends and her friends' enemies. She's a double-faced person.3. Spies are double agents so they can accomplish their missions without getting caught.
 a double dealer a two faced person a double agent hypocritea double dealer = 說一套做一套的騙子a two faced person = 見人說人話、見鬼說鬼話，討好身邊的所有人，八面玲瓏，已受歡迎或得到好的名聲為目標a double agent 是雙面的間諜hypocrite = 偽君子
If you want to grow out your bngs you need to be patient.