We borrow 25 million using either overnight or 2 year term repo, the levered portfolio would have a longer duration if the overnight repo is used instead of the 2 year term repo.
The reason that the levered portfolio would have a longer duration if the overnight repo is used, is it because the overnight repo duration is zero, such that
(D(A)*A - D(L)*L) / Equity
as D(L) of overnight repo is zero, so the portfolio duration is higher.