The following error may be received when attempting to process a membership transaction (such as a renewal or rejoin) in Daily Sales:
Error: An item with the same key has already been added.
This error is being caused from a duplicate relationship existing on the Constituent. To resolve the error open the Constituent's record, go to the Relationships tab, and delete the duplicate relationship.
If removing the relationship does not resolve the error, Chat with Support and reference this article.