The system is not allowing to do the Quality inspection

Followings are the details:
1) We created the PO of Stock items and in PO the same material number
is created 2 times in one line quantity is 3 and other line quantity is
2.
2) we post the GRN (Transaction code MB01 and Movement type 103) for
the above 2 materials in same GRN with complete quantity (3 and 2
Quantity).
3) system generated the Material document with 2 lines as well as the
Inspection Lot for the same materia. This lot having the Quantity of
both lines as sum up (5 quantity in one lot).
4) user has taken the action and have done the usage decision (QA11)
for 3 quantity ( the system posted the Material quantity 3 in un-
restricted stock Movement type 105) and now the user is trying to do
the usage decision (QA12) from remaining 2, but system is allowing do
do post the reamining quantity and displaying the following message:

***************************************************************
1 EA Incorrect posting to unrestr-use stock, error msg:
PU GR blocked stock exceeded by 1 EA : 818194 QG10 RF01 M7 22

The status is showing 'Stock postings not yet completed for lot'

Appreciate your feedback.

Thanks,