Whatever you do, don't swap cleats you'll drive yourself bat-***** crazy. I'd just suck it up and buy two sets of pedals, or just one set and a pair of shoes to go with it.

Or you could get nice pedals for the nice bike and less nice pedals that use the same cleat for the other bike - I have old Look Keo Sprints on my old bike and new Look Keo Max 2 carbons on my new bike, they use the same cleat.