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.
Employers do not have a day to browse all cover letters, which is why people have to brief in the message they want for employers to know. Likewise, they need to be consistent and true to the details and information they will allot in the cover letter. To have the most accurate letter format, they should take enough time to plan its overall construction. They have to know that it can help them land the job they need. Taking shortcuts in some of the information they wish to convey will do them no good. It is strongly suggested to gather up their senses in creating the best cover letter.