I don't see a problem with B&M's having similar layouts at all. All of the older B&M's built in the early 90's had many features no one had ever seen before. A few Vekomas had their version of the cobra roll (boomerang in Vekoma speak) and Arrow had their own batwing element, but who had ever seen anything like interlocking corkscrews, dive loops, immelmans, zero-g-rolls, inclined loops, or loops circling lift hills. Plus every element B&M built was far larger and more impressive than the competition's. You could not have asked for them to be any more innovative. Each time they come out with a distinctively different type of coaster they always come up with some new features for it.
B&M simply found combinations that works and the continued strong sales of their decade-old models more than justifies sticking with a proven formula. They throw something new at us every now and then. Besides the same exact elements often feel very different from one ride to the next.