Share your insights or perspective on the financial matter presented in the input.

Is there any downside snapping a picture (or scanning a copy) of every check one writes vs. using a duplicate check?
No, there is no downside. I personally don't use duplicate checks.  I simply make a record of the checks I write in the check register.  A copy of the check, whether a duplicate or a photo, isn't really proof of payment for anyone but yourself, as it is very easy to write a check after the fact and put a different date on it.