Actually, bjanet, all snapbeans are "kidney" beans. Some kidney beans just have thicker pods that are suitable for eating before the seeds are mature.
The Rattlesnake beans I grew last year are snapbeans but I harvested most of them when they had fully developed seeds. After they thoroughly dried, they made good bean soup.
I've grown a few varieties like Pinto and Soldier that are not intended for use as snapbeans. The Soldier beans especially did really, really great but, I think that location may have a lot to do with performance. What kind of kidney beans are you thinking of growing?
Steve