Well here's a guess. I think there's probably only one Ethel. The "do not publish" on the second record probably means they didn't want the marriage information forwarded to the local newspaper. The 1930 census shows Ethel was first married at age 20, so she "may" have been married circa 1922. If so, it could explain the different last name on the first marriage record to Elbert Burris. I can think of 2 possible explanations for the 2nd marriage: they divorced and remarried or there was some question as to the validity of the 1st marriage and so they married again to be sure it was legal.