Alison theory

This was found on the internet.

So, I have had this theory for a long time that Alison & her twin switched places on Halloween night. I don't know why I think that. It's just been in my head forever. But the radley car was in the front of the creepy house and this was before Mona went all 'crazy' obviously. Why else would it have been there? Because her sister escaped and they ended up swapping places, I think the real Ali is alive and her crazy sister is dead. She was like a different person after she pulled her prank...

Alison's story in Halloween special! This is symbolic. Both of the twins are having fun playing with the dolls(that obviously resemble each of the girls aria, spencer, emily and hanna). but when it comes to playing with the main, biggest, blonde doll, they fight. they are fighting over being Alison. Now i think that the twins were friends. they enjoyed fooling the girls and took turns being Ali. but one of them decided they wanted to be Alison all the time

Hmmm...

I would support this theory.