LOL

Maybe I just love colourful chaos on my shelves.
I just can't imagine anyone standing staring at their shelves breaking up over the spines on their books.

I think Marvel do this on purpose just to annoy you, and I can see the spines changing again and again with Marvel Now! and more re-launches ahead.
So you're only working yourself up, because Marvel aren't about to make all their books look perfect for you.

If you NEED uniformity, I guess the only option which someone else already suggested is printing your own covers...