To further illustrate the issue, I have attached a screenshot from my collection.

I have two 3x12" vinyl sets. Each individual vinyl has been added separately, then grouped as a boxed-set.

As can be seen at the bottom of the image, the disc count is 6. I have highlighted all the parts of one set, and the disc count is 3/6.

This is how OrangeCD appears to count ALL multiple disc sets.

I have just deleted these two albums from my collection, and the total disc count was reduced by six.