While attempting to merge two constituents you may receive the error message Data could not be saved. The UPDATE statement conflicted with the CHECK constraint CK_SALESORDERITEMMEMBERSHIPCARD_VALIDNUMBEROFCARDS. The conflict occurred in database XXXX table dbo.SALESORDERITEMMEMBERSHIPCARD; column 'SALESORDERITEMMEMBERID'.
We are currently evaluating this issue and will update this article when we have more information.
Steps to Duplicate
Click Constituents > Duplicates >Merge two constituents