I have similar weight belts with a clip on one end and a D-ring on the other end. I’m sure they are for accessories like an extra flash light or line reel or something. I have never used them though. I don’t want anything else attached to my weight belt that may make it more difficult to dump the weight in an emergency. Plus, I’d rather just loose my weights and weight belt and not whatever I had attached to the clips :)
My BCD has plenty of clips and D-rings that I use for my accessories.