Well, I don't work with PAL, but I'm guessing no. The problem is that the fields have apparently been combined in the changeover from NTSC to PAL. It's kinda like working with layers in Photoshop - once you combine the layers and save the pic, you can't go back and separate the layers. They are now one picture. (I could be wrong, but this makes sense to me.)
You are either going to have to go to the original NTSC source and correctly IVTC it and convert to PAL, or just suffer with the current PAL version, problems and all. Sorry.
[EDIT] It just ocurred to me: the scanlines may be merged, but they don't overlap, so it probably is possibly to take those problem frames and remove even- or odd-numbered scanlines. That being said, doing so may create extra frames, changing your fps to something other than 25, creating even more problems. I guess you could remove, say, the odd-numbered lines and delete that field altogether, but you may end up with jerky motion. I don't know if it will be worth the effort or not.