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You notice that GR 101 documents, which were posted with SES acceptance and GR 102 documents, which were posted with same SES acceptance revokal, have different values.
If there was an invoice posted between SES acceptance (GR 101) and SES acceptance revokal (GR 102) and the invoice had either final invoice indicator (RSEG-EREKZ) or GR/IR clearing indicator (RSEG-WEREC) set, then this is normal behaviour. Please check notes 440942, 856682 and 1833155 explaining the reasons for this. Second note also offers workarounds to have the display of the PO history corrected (as GR/IR account is cleared already, this is a display issue only but it can be indeed confusing for end-users).
Related notes / content:
440942 GR cancellation not equal to GR
856682 Goods receipt document cancelled with incorrect value
1833155 MM-SRV: Goods Receipt (GR) cancelled with incorrect value