I am not sure if this applies to every vehicle but so far i have seen it in the Civilian SUV and the Strider.
The right mirror (opposite the driver) display the same Picture in picture image as the left mirror (next to the driver) making the right mirror kind of pointless.
Example 1: if you are in the driver seat of an SUV and there is a man on the left side of the car. If you look into the left mirror you will see him, normal right? now look in the right mirror. He is also "Reflected" in that mirror.
Example 2: You are in the driver seat of an SUV and there is a man to the right of the car. None of the mirrors "Reflect" him (since the right mirror mimics the left one.)
15/1/14: I have recently retested this, finding something interesting.
On most vehicles the mirrors reflect the same image because they are practically in the same spot due to incorrect placement of which there are various other issues about however, the one vehicle that this mirror bug is most visible with is the SUV because i have done a test with a box on the left side of the vehicle and looked in the left mirror (seeing the box) i then looked in the right mirror and the box was there as well.
so as of now the bug still persists.