I did not use two types of lentils to make it complicated for you, I believe they add a different texture and color. The reds will break down and add some heartiness to the broth, whereas the green/black will hold their individual shape. Both are lovely, but if you find this to be a hassle, go with just green. Once you blend a bit of the soup, the broth with still get some bulk to it regardless. The color will be a little more murky. If you like a bit of heat, add one chopped jalapeño to the vegetable mixture.