My current phone, a rather excellent Nexus 5X, has a half-decent camera. While playing with it today, I did notice a bit of an imperfection though: it seems prone to internal reflection of particularly bright objects!

In other words, for a really bright object, one will see the main image of it, and then a smaller, darker reflection: courtesy of the light bouncing back off of the sensor, out to the lens, and then a dim reflection bounces from the rear side of the lens back onto the sensor again. Kinda like double vision.