Hey Luigiwu,
Give them another chance! I too had a horrible yield from my Rattlesnake and Scarlet Runners, but it simply wasn't fair to plant them in a (large) pot, far away from a water source and expect them to grow on a shady arbour with no supplemental watering. The Scarlet Runners didn't do much better the following year when I thought it would be fun to grow them up a large Honey Locust tree as they still didn't get enough light or water.
Last year I planted Purple Peacock because a friend gave them to me and told me that she couldn't keep up with their production. I planted a dozen plants in my veggie garden and lost a couple. They were amazing, grown in full sun with adequate water!
I do think that you might be expecting too much by only planting two bean plants. IMHO you probably need more than two plants to be able to pick a meal's worth for two people whenever you feel like it (or maybe I'm just a little piggy when it comes to eating beans!)
Linda