The Doctor From Gallifrey 

DO NOT READ IF YOU DON’T WANT TO KNOW WHAT HAPPENS- CONTAINS SPOILERS 

The Almost People was fairly simple to explain. Essentially the Doctor and the ganger version of himself helped everyone else to escape to the TARDIS. Jennifer's ganger made a second ganger and tried to unite the other gangers to kill the human versions of themselves. They weren't having it and Jennifer turned into a horrific monster. By the time they all escaped in the TARDIS there was one version of everyone left, some human, some ganger. 

There was a shock ending though as it was revealed that Amy was actually a ganger. The Doctor melted her and we saw Amy being ready to give birth in some mysterious hospital-like place, being looked over by the myseterious eye-patch lady. What does it all mean?

It should also be noted that because the Doctor and his ganger switched places, Amy accidentally told the real Doctor that he was going to die. This may be important later on. 

We shall hopefully find out more in the next episode, A Good Man Goes to War. Can't wait!