Sorry for digging up such an old thread, but I also had this question (I even subscribed to the thread some time ago) and now I found the answer to it, so I thought it would be a good idea to add the info here, in case someone else has the same doubt.
I searched online and discovered Tom Jubert's website (he's the writer of Penumbra), and he wrote an article where he says that there are in fact two characteres named Amabel.
Quote:Incidentally, if you noticed there was another character called Amabel in the game – yes, I screwed up. I like the name, OK?!
http://www.tomjubert.com/swanson
So there's Amabel Swanson and Amabel Carlito.