I have a problem and need help.

I exported inventory items from Export to Excel. The list has 16,508 items. Exported to Excel from the Item Inquiry window and I have 16,513 items on the list. Exported to excel from the Item Maintenance window and have 16,904 items!

What have I done wrong?
I have found many item in duplicates and triplicates in the Item Maintenance export list. And they are not in numerical order. Just repeats in some other rows. Now I am not sure how many inventory items we have.