You do not have to worry much about being a copycat if you do not find the most unique cover letter format in town. Just be sure that the contents of the letter have a clear and definite direction. This will bring about a good flow in the contents of the letter.
In this article, I'll give you a few tips that your should consider with respect to your cover letter format. It always amazes me how many people truly miss their opportunity at desired jobs because they motivation letters that have sub_optimal formatting.