Most of us know that, the Motierre guy before the emperor's assassination and afterwards is completely different. No doubt Motierre used a body double to meet the dragonborn at the bannered mare but!

Today i used a no helmet mod and did the DB questline. What follows was shocking. I found out that Motierre and Rexus swapped places at the bannered mare. Motierre was no longer the same looking face but when i glanced at rexus, the face looked nearly similar. Similarly, If you look at rexus' face at voluundrud and at the bannered mare, they changed too. The old Rexus' face is now shown on the new Motierre.

If this was indeed not a bug, i have to say, the dragonborn killed the wrong person at the end for the gems.