This shouldn't happen anyway. Did you do the GR for both PO together?
Is it possible that one PO was received earlier and other after sometime? Because in that case, inspection lot would be generated with quantity of first PO. When second PO is received, only the quantity is updated in the inspection lot, if the batch number is same.
Is system status carrying SPST, instead of SPRQ or SPCO?
Amol has suggested a clear solution but you also need to find a probable cause so that it doesn't repeat.
KJ