.
...using adjustable cups with lock rings on bikes with RH threading on both sides was a commonly used trick to create a BB with an adjustment for chain line.
This is doubtless what someone has done on yours. It works well, so unless you are swapping the entire unit out for something else, I would just use it as is.

OMAS is not seen all that often, but it was commonly available back then. It's relatively high quality stuff....probably on a par or better with Campagnolo in terms of durability.