Purchase quantity 100, inventory 400

Hi, We got a strange problem in our inventory.

An item which was purchased into inventory at the quantity of 100 pcs, became 400 in inventory?

The item register identifies 400 entered on that purchase, but when you open the purchase, it clearly says 100 pcs

The usual reason this might happen, is multiple entries of the same item on the same purchase, Then the total of those will equal the total on the item register for that purchase. But, NOT in this case, so we are at a loss to explain it??

I have attached two screenshots, one showing the purchase, and the other showing the item register. Note the item value is the same for the 100 pcs on the purchase and the 400 on the item register.