I buy exclusively from sticker boy. They have a better selection of skins. I've been getting skins now since I bought my iPad 2 a year ago and for the past year I've noticed that icarbons is always playing catch up with sticker boy. They have the same templates but sticker boy had them first. One year ago icarbons templates were VERY different from what they are today... until they copied sticker boy. Also, one year ago icarbons ONLY sold carbon textured skins. Now they also copied designs from sticker boy.
Just to clarify, none of us use the "same templates" to produce our skins. Apple doesn't provide any such templates, just a basic CAD layout that is available to all case manufacturers. While I can't speak to the design/manufacturing process of other companies, I personally find it easiest to work directly from the device, using Apple's CAD files as a reference.
As for finishes, it really comes down to how deep the pockets of the company are, as these films used to make these skins are pricey, and there are minimum order requirements from the film manufacturers like 3M. Film availability is also an issue in different markets. Here in Canada, I have a very limited selection to work from, so if I need to expand the selection, it means importing the film from overseas typically, which requires a larger order, and a bigger investment.
It's a bit of a stretch to say that iCarbons copied Sticker Boy, either with templates or finishes. As the market changes, they need to adapt. Last year, Carbon was the rage. This year, people are looking for something different, and companies like Sticker Boy, iCarbons, and myself adjust accordingly.