Why is iPhoto creating new copies of faces in my mother's photos?

My mother uses iPhoto to look at and edit her pictures. She is getting very frustrated because it seems to be making new pictures of all the faces in her photos including a lot of faces she doesn't know or want (e.g., people gathered around tables at parties). She's being overwhelmed with new copies of existing photos and these new face crops. I've looked at the Preferences and can't find anything to turn off to stop this behavior (I don't use iPhoto myself because I don't like the behavior).

For that matter, I can't seem to find out why it's creating duplicates of pictures already in her Library. To my knowledge, she's not Importing them again so there's no reason for these duplicates to keep cropping up. She was using OS X 10.6.8 on her iMac but I've just upgraded her to Mavericks.