Yes, I know that most of those apps has similar codes, but I mean if it is a problem that i upload lots of similar apps with my developer account, but making some minor changes (in the wallpapers example, changing images, name of the app, package name…).
I think in your case it shouldn’t be a problem, i mean, Google will ban people who upload similar content, but since you are changing the images and theme of the wallpapers you are indeed offering something new and possibly valuable to the users
even I know many forum members here which do use this technique to get more revenue. You can even copy paste app description across such apps. Google will wake up only when someone throws water on their face.