Some invoices were duplicated after upgrade to 1.5.1


I have make an upgrade from 1.4.10 to 1.5.1 and I have found some invoices which were duplicated.

Have a look :

Those duplicates have the same invoice ID (on the front-end link for example)
But phpmyadmin, I don’t see any duplicate on the ip_invoice table

I didn’t try to delete one duplicate in case of deleting all the occurence.

What sould I do ?

I have a clue : all invoiced which received several paiement are duplicate.
So maybe it’s a normal behavior of the new version ?