Have you watched the short tutorial on Bank reconciling?
https://youtu.be/Jk5s1RkBQrs
The idea is your imported transactions get dragged on to the calendar where you already have your future plans. Rather than simply dragging them on to the calendar, if you drag them onto an existing entry it will update that entry. This will prevent a duplication and rather will simply update any transactions that you had as part of your plan. Dragging Bank import entries onto an existing entry will update both the date and the amount of the entry with what actually happened in your bank account.