How to append column but getting values from previous export

I am having trouble with this:
When I export my first file, my column for Username would be filled like this:
(1st Export)
Username
Tester1
Tester2
Tester3

When I export a second file (which will only append from the 1st export) and the column value for Username is changed, I want the output to be from the 1st export.
(2nd Export)
Username
Tester A
Tester B
Tester C

Expected output would still be (note that I only want this to work on this specific column)
Username
Tester1 --1st export
Tester2
Tester3
Tester1 --2nd appended export
Tester2
Tester3

This is expected for the next 3rd, 4th and so on exports :slight_smile:

Can you upload a workflow?

Duplicate: see Append table while retaining a specific column