See, I've never found that to be true, not when I'm using a jam with some texture to it. If it's more like a grape jelly, sure, but if it's something with actual chunks of fruit in it, it tends to be a lot easier and faster for me to do the peanut butter first.

I can't think of a single time in my life I've used two knives for making PB&J. I've used a spoon and a knife before, when I was scraping out the last bits of a jar, or counting calories so measuring amounts of each, but never two knives.