Dunno where the (2) came from? But yes, you got it right, back up the ADE_FTX_PFJ_PAKT_Ketchikan_Intl.BGL and drop the (2) in it's place, whether you rename it of not won't make any difference, but you musn't have both files active at the same time, that will cause problems. So for the best I would rename it to match the original, then you will know for sure for any future changes exactly which scenery file is active.