Hi sistersue, just wanted to say welcome to the forum. I am not sure that double replacement is any worse, really, than just replacing one. Maybe a little longer in the OR, but it is the anaesthetics, the other drugs, being on the bypass machine, being in an unnatural position for that length of time and having your sternum opened that cause many of us to describe the experience by thinking it feels like getting hit with a truck! Recovery should be about the same, as well.
In fact, many people find that after recovery, the fell better than ever.