Hello,
The duplicate inventory id’s are probably being caused by a table relationship which is duplicating the sales order lines and thus inventory id’s.
You need to investigate which table is causing the problem. You may have a one to many relationships between sales order line and another table.
Confirm, that the problem is with sales order lines by adding Sales Order line number to the report. If you have duplicates then the issue will be there.
Then investigate the relationships between the sales order line and other tables. Confirm the keys used in the table relationships using the Acumatica DAC schema browser.
Good luck!