No, I would want it like this:

The client would then just need to download one decal, which would consist of four sides. The decal maker would deal with a strip, or, an image that is split into multiple parts.
Another thing that I would like, denoted in my image, is a system in which decals could hang out side of the player's head. Here's an example:

Though 2d, it would provide a neat effect, and more flexibility for the decal author.