I just happened to have changed my bitz nock reciever from left to straight. As I compared the detents between the two I couldn't find a difference. When I think on it some I can't see why there would be really - basically what kenn1320 is saying, it's all about stopping at certain points on the 360 degree rotation.
Makes my wonder why I bought the straight receiver now. I think you can use a left, right and straight clamp just fine with one receiver.