How does the Union list operation check for duplicates?

Mendix 9 documentation mentions that the Union list operation is “The result is a combination of the elements of both parameters avoiding duplicates.” But how does it check for duplicates? Does it use the surrogate key that’s automatically generated for it or does it compare against each attribute in the entity?
1 answers

It uses the GUID or unique identifier for each object generated by Mendix.  If you want to compare attribute values, you’ll need to do that yourself in a microflow.