Well I've never heard of, seen, or done 'two stroke peeling' - but I use both blades depending what/how I'm peeling: you can either brush away from you, or pull in against your thumb as you would if using a paring knife.

That could also be explained by left handed people wanting to join in on the vegetable peeling fun.

I'm thinking peelers with horizontal blades. Not the knife keepers with the blades parallel to the handle.