This app was mentioned in 1 comment, with an average of 1.00 upvote
Ugh! I know the pain. I've got a free and paid app in the app store, and remembering to change the package ID and title before building was a nightmare -- I think I released a version which was the free version with the paid version's ID and icon.
So I wrote a gulpfile that edits the required files and builds the free or paid version for me. So much easier, and 0 mistakes since.