Efectivamente. There are actually quite a few brands who sell bricks that work in a similar way to Lego under a different name.
This is because the purely functional aspects can not be protected. That would be like protecting physics, which of course is ridiculous. The design aspects or course can. Now, don't ask me to explain the differences. I have no idea, and I believe many companies, not only Lego, ran into that.
In some context, you can't protect the concept of a car with 4 wheels and an engine of sorts. But the design and the branding, that you can protect.