Exhaust fumes? *Sweatdrop*
If by "comparing couples" you mean what the coloring looks like on the same example pages side by side, that would be fantastic, actually. If it's not what you meant, then all I can say is "Huuuuuuuuuuuuuuuh? *stupidly blank non-understanding expression*"
But really, I just thought of the single easiest thing to ask -- did the one from Father Tree *ever* have the same-looking cover as Starblaze, because I'm sure I had the ones with the swoopy-looking Leetah on the front all in reds and yellows (for book one) and so forth.