Append table measures

Couple of ideas on this. Depends on how you did your Append though. If you did "Append as New" you could just sum from your original tables. If you did not, then in your original table, create a column called "Source" and just set it equal to "Source1" create the same column "Source" in your other query but set it to "Source2". When you append the tables then you will know which source each row came from, either Source1 or Source2 and then you can use CALCULATE to FILTER your aggregation.