Aurora NY to Stamford, Canada West - rare Aurora "paid 5" markings

Aurora, NY 30mm circle town postmark with a pair of fancy colorless "5" paid markings in a sawtoothed circle (CV $250). Also on the front, a straightline "United States 6p" applied at the first Canadian post office in Hamilton, Canada West.

On the back, two double circle received markings - Hamilton, Canada West with C. W. at the bottom and the second post office closest to Stamford, Upper Canada with U. C. at the bottom.

And then, there's the prescient note at the bottom - "Answered before received."