Possibly one way around this:
SAVE your original as 2018-1 or something under SAVE AS
Then re-open it (2018-1), SAVE AS 2018-2 & continue to look at your return. You have saved your original return as 2018-1, but any changes or no changes on 2018-2. I always do this. And at the end, save your final one as 2018-FINAL
