Inspection Lot Quantity for Partial Goods Receipt

Dear QM Experts,

I have a query for the inspection lot quantity.

I used a control inspection lot : 2 (For each material, batch , storage location)

The company only want one inspection lot for several goods receipt PO for material with one batch.

Ex:

1st GR : 12400

2nd GR : 7600

In the inspection lot the data is become like this :

Actual Qty : 20000

Inspection lot Qty : 12400

Sample Qty : 315

The question is why the inspection lot quantity is different with the total GR quantity??

Is it possible to correct it ? Or is there any customize for this qty?

Tks & rgds,

Helly