It sounds like you're experiencing a bug that was included in an old version of the app!
Those duplicate expense entries were likely the result of a bug that was included in version 2.14.0 of the app. That bug has since been resolved, and if you update your app to the most recent version (2.14.3) by going to the App Store here, you shouldn't see those duplicate entries occur going forward.
Unfortunately, you'll need to manually delete those duplicate entries from your account. You can do so by swiping left on the expense record on your Tax Savings screen, and then clicking the red "Delete" button.
We realize these duplicate entries cause a significant inconvenience to you, and we sincerely apologize that this bug has added so many extra steps to your day! Thank you again for bearing with us throughout this issue.