I have had a few items with incorrect inventory numbers and I am having trouble drilling down to the issue.  One possible issue I have found is a separate transaction in the transaction list other than the normal "PO, SO, IP".  All the items I have had trouble with have a transaction type "IA" on them and it is always updated by our accounting person, which she should not be updating any Inventory adjustments.  They stated that they just update the batch and don't really look to see which entries are in the batch, I asked them to watch the batches to see if any entries are not theirs, no have been found in a month.  Any user who receives a PO or makes an inventory adjustment updates their own batch so not sure why accounting would pick up one of theirs, but I could see this causing the duplication of inventory additions to an item.