Here are links for the Simprop compatible ones:
According to a post on a Swedish forum, these receivers uses OEM chips from Futaba, and in that case they appear to be licensed. Since Simprop is a German company, I would suspect that they made sure they are not violating any patents. The pricing of these are very close to Futaba's own receivers.
I would suspect many Futaba users are waiting for clones or copies from China, and I guess this is what the OP is asking for.