From a regular 1040 view, you should be able to highlight the duplicate that you dont want anymore and hit the Delete key on teh keyboard OR right click on it and choose Delete. This wont work from the EFCenter, only a regular HB view.

You really shouldnt change the names on them each year, the 3 digit extension on the end of the file name i.e. .21i .20i .19i shows you what year the file is for, you should leave the same exact filename to roll to each year.