The Bobro was likely designed for parts interchangability between different models. Makes it cheaper to manufacture, simply mix/match parts to get a 1" ring, 30mm ring, or even a different mounting base for 20MOA elevation etc...
I recall seeing something similar from one of the manufacturers - don't recall who, but the mount I saw could be adjusted to 0 MOA, 10MOA and 20MOA elevation by simply unbolting the rings from the QD base, moving it around to the correct index and retightening and tada the elevation is set.