Kylie & Kendall Jenner Face the Music

Kylie and Kendall Jenner are back at it, hitting a famous music venue in West Hollywood last night -- and this time, they definitely were NOT ID'd at the door.

16-year-old Kylie and 17-year-old Kendall went to watch their brother Brandon perform with his wife Leah ("Brandon and Leah") at the Troubadour -- Bruce was there too -- but the good news, no fakes were required ... because it was an all-ages event.

... Unlike the one at Vignette nightclub earlier this week.

On their way into Trouabdour, we asked the girls about their visit to the 21-and-over venue Tuesday -- but they didn't have much to say. We asked Bruce what he thought too. He didn't look too happy about the situation.

As we reported, the California Department of Alcoholic Beverage Control has is on the hunt trying to figure out if the underage Jenner girls used fake IDs to enter Vignette -- even requesting security footage from the bar.