Justin Bieber -- The Walls are Closing in ... Parties with Kendall Jenner

Justin Bieber may be juggling sisters, because he partied Tuesday night with Kendall Jenner at the same night club where he hooked up with Kourtney Kardashian over the weekend.

Justin and Kendall arrived separately at The Nice Guy in WeHo at around the same time -- 10 PM.

They left separately, too ... just like Friday night when Justin and Kourtney left Justin's go-to club and headed for his Bev Hills hotel, where she stayed 'till 4 AM.