Error when using ProTools Item Combiner

Question: I am merging one item code to another. The item validates. I run the merge
and get an error "Cannot insert duplicate key row in object 'IV10201' with
unique index 'AK3IV10201'."

If it's merging one code into another table, how could it possibly have key
violation since it's changing the code?

The same error is happening on every item I try.

Answer(from my friend Richard Whaley):
This is one of the headaches of combining items.

The IV10201 table is the purchase receipts. So, if Item A had a receipt and
Item B had a receipt, you are also combining the receipt list. This should
work EXCEPT...

The AK3IV10201 index is a unique index, meaning there can only be ONE entry
in the index with the same item number, receipt number, and receipt type.
So, if item A had a receipt #5 via PO and item B had are receipt #5 via PO,
you get this error.

How to fix it? you need to purge receiving history, something you might not
want to do.