There should be an option for whether you would like your duel history and duel stats posted on the duelstats page.

Basically if not, then you would not show up on the main page of duellers, and your history would not be available.
It would still be there, but no hyperlink should be created when you appear in others' duel histories.

Just basic character privacy, instead of being publicised.

Why?

Don't duel then

If you don't duel after 30 days you drop off the list

The point of /duel is bragging rights, so hiding the records would be counterproductive.

-1