Yep, we are in the same boat too!
Alana has been difficult from the day she was born. Caitlin was always so placid as a little baby, and would just happily sit in her rocker. Alana, on the other hand, would scream as loud as her little lugs would allow, and demand to be picked up and cuddled etc. Because Caitlin was content, she unfortunately missed out all too often.
My girls are 3 months older than yours Cat, and we still have the same problem. Unfortunately, Alana just hasn't learned. She still likes to think she is the boss, and is always snatching things off Caitlin. If I see her do this, I will ask her to give the toy back to Caitlin. If she screams and carries on, she will get time out. However, she doesn't seem to learn anything from time out. She has had time out more times than I can remember. Caitlin, on the other hand, has only had time out several times. She also seems quite remorseful after the punishment.
So yes, I do often wish Alana could be more like Caitlin.

I just try to deal with her as best as I can. I was kinda hoping that it all will get better with age, but from what Belinda has said, that is just a pipe dream!!