Jeremih Opened For PartyNextDoor Thursday Night -- Except It Wasn't Jeremih... It Was His Body Double!

Rhythm is a dancer… and Jeremih is a liar! While PartyNextDoor is known for making some less-than-stellar decisions, it was actually his opening act that had fans seeing double during his concert Thursday night. Literally. That's because we're hearing that while the Don't Tell 'em singer got through his 2-song set at Revention Center in Houston, Texas…