@StephanieAlba   So that means sense... so using your data scenario above if we have something like this that uses a IS DISTINCT FROM instead of the "=" (shown below) then we will get an error, correct?  It will still try to update two records, which is not allowed.  Correct?

MERGE .... ON source.id = target.id
WHEN MATCHED AND source.value IS DISTINCT FROM target.value
WHEN NOT MATCHED THEN INSERT