That's a reason why I'd move the favs from the twitter upload to the the pixiv one.
Well, by now, the twitter upload (child version) got decresed in it's score by two now and it was by 56 I guess before this here was uploaded.
So, the uploads of the same picture do handicap each other, espacially, when the pixiv upload is upload much more later then the twitter upload (like here).

Maybe a forum topic would be better, though?