Why are the Convair 880's yokes shaped differently from each other?
My guess is that this is a relatively odd situation, where one yoke had already been replaced by a newer one (on the right), whereas the other still is the original. 

If you look at the two images below (from Airliners.net), both yokes are the same.




It seems as if the right one has some more controls on the yoke (e.g. for radio settings, trim controls, or something else) and is simply an upgrade to the older model. If the old one still worked, I can imagine an airline waiting for a regular service inspection or overhaul before replacing it, rather than removing parts that are still fit to fly.