I was having problems downloading email from my ISP's email server because I had inadvertently set all my accounts up as POP3 protocol. This was after having to recover my Win 10 system and its apps. I finally found out that setting the accounts to IMAP protocol would solve the problem. (It seems that iOS devices that access the mail using IMAP were confusing settings at the email server.) I went through and made the changes to each of the accounts setting the IMAP option. In doing so, I created duplicates for some of the 5 accounts I use but not all of them. I found an answer here that said to use Thunderbird Tools>Options>Account_Settings, select the account to be removed then to use Account Actions to remove them. When I try this, at the point of selecting the account to be removed, I get a message saying, "An account with this name already exists. Please enter a different account name." This message prevents me selecting the account to be removed. Can anyone tell me how to get around this and to remove the duplicated accounts?