I would love to see logic put a feature in that allows you to copy an audio track in the arrange
page with a special key command
There is a slightly indirect way you can do this now. If you take two or more audio files you can use a key command for merge or use the glue tool and that will create a new audio file. You could either make two copies of the same original audio, or else make tiny audio file with silence to tack on to the end, and keep that in your autoload. Then glue them together, you get a new audio file. Then you cut off the excess or resize. Actually I have gotten into the habit of always doing this anyway - recording half a bar before and after - then snipping them off later. This is because Logic sometimes doesn't clear the buffers from a previous take so you hear something at the start of the recording, and also there might be some issues with when the note starts and tails at the end. So I snip off the ends, then open the sample editor, and slide the selected region down so that the beats starts right on the money sample accurately.