Count opened stock before reserves
Choose one item that often gets duplicated and pull its ordinary stock into view. For oil, count the bottle by the stove and the unopened bottles in the cupboard. Check the actual product too. A finishing oil and an everyday cooking oil may have different uses even if they sit on the same shelf.
Use a two-place shopping note
If more than one bottle is already open, mark which one to use first. Do not buy an organizer until the extra stock is gone. The useful habit is a visible counting point, especially for items people store in several rooms.
Try “Open bottle by stove; backup in upper cupboard; buy only when backup opens.” The note does not require a full pantry inventory. It gives the person making the list two real places to check and tells them exactly what should trigger the next purchase.
Handle bottles that genuinely belong apart
If one bottle is kept near a second cooking area for a reason, mark it as stock there rather than moving it merely to enforce the system. Tell both cooks which bottle gets counted for the shopping list. After two trips, check whether duplicate purchases stopped and whether anyone had trouble finding what they needed.