If you open one image, then drag the rest in and select add layers, then you would be working on "one" image, right? So a plungin would be able to differentiate the layers and look for similarities. Should be "easy", right?
Photoshop has an easy way to remove people from a picture (a series of pictures actually). It's described here: http://i.imgur.com/aus6p8Q.jpg If someone wrote a plugin for this to paint.net, it would be awesome... Any one working on it? -Tor