Stitch Join Data in Data Studio
Go to the packages tab in Data studio pick your data exports that you wish to export.
Select your two exports to put into one package.
Select one Merged CSV file. This will combine a table based on a set of fields. Now pick the fields that you wish to merge into the package.
You have the ability create the mappings in a very custom fashion. Or you can do a quick mapping of the fields. To quickly map all use the select all and click accept.
You can choose how you wish to map the fields.
Data Studio also creates a field that tells you where it came from.
Lastly Data Studio has taken extra care in mapping the correct field like email address for each table. Recipient and Response email is the proper mapping of email fields in this case and data studio picked that for you.