No, there is no warning. However, there is now a Name Check feature included in the game now. By using this feature, found at the character select screen when logging into a specific server, you can check if a name is available on the server you are currently logged on to prior to purchasing a rename token. Be sure you are logged into the correct server when you are checking names.

Please keep in mind that while a name check may come through as showing a name available, there is still no guarantee that someone might not choose that name just before you use your rename to obtain it. Therefore, there are no guarantees that any name will be available. All purchases of Character Renames and Character Transfers are final and non-refundable.

If you do go through with a Character Transfer and there is a name conflict on the destination server, the character’s name will be appended to have a numeral at the end and be issued a free rename token. When you next log that character in, you will be able to use the rename feature to obtain a new name.