Clone Index
You can access the Full Text Indexes from the Search tab. Left-click on this to display the Full Text Search panel, which contains a tabular presentation of currently existing indexes, with a row for each index. (See Searching from the UI for a full illustration.)
To clone an index, left-click on its row. The row expands, as follows:
Clone button click brings up the Clone Index screen, which allows a copy of the current index to be modified as appropriate and required, and saved under a new name.