Can I get rid of the duplicate transactions that occurred when I connected to my bank account? How do I do that? Reconciled ones have the "R" and the bank ones have "C"

If bank transactions that have already been reconciled are re-imported, select the box(es) to the left, then choose Exclude in the dark banner that appears across the screen.   You can select more than one and exclude them all at once to speed things up.  This removes these transactions from the For review list and puts them in Excluded.  Make a mistake?  Go to Excluded list and undo.