Originally Posted by DA Aquamaster
Rob, it does not have anything to do with telling them apart.
For example with a Seacure mouthpiece you can shorten one of the bite tabs more on the left or right side as appropriate, you can trim the edge on the right of left side of the mouth piece or you can cut a small divot on the left or right inside edge of the mouth piece - which is what I do.
The critical issue is that what ever you think you might need to share someday be short enough to fit in the OOA diver's mouth.
Even if you dive a long and a short hose, I'd argue you want them both to be short enough to donate just on general principle.