This warning is seen when there are multiple records with the same key column is present in the reference table from which lookup is done. Lookup, by default, will fetch the first record which it gets as match and will throw the warning
since it doesn’t know which value is the correct one to be returned from the reference.
To solve this problem you can either one of the reference links from “Multiple rows returned from link” dropdown, in Lookup constraints. In this case Lookup will return multiple rows for each row that is matched.
Else use some method to eradicate duplicate multiple rows with same key columns according to the business requirements.
