Error adding more than one Wim to a USB Stick


I'm editing the bcd on an External USB Flash Drive. I am able to add one WIM entry. If I try and add an additional Wim entry, I get an error: An error occured while attempting the specified create operation. The specified entry already exists. Cannot create a file when that file already exists. I can delete entries fine. If I restore the bcd from a backup copy I can again make one addition before I get the error.