Strange attractor achievement

Twice this year I have set out on an expedition and on the journey, unplanned and unintended, I finished up at an older hashpoint I had visited and I was NOT aiming for.

Aiming for 2015-06-29 52 0 I reached 2012-08-08 52 0 - my track log showed me passing within two metres.
Aiming for 2015-05-29 52 0 I reached 2012-11-04 52 0 - I missed my turning and my U turn was at the older point.

This is more than a Déjà vu achievement because it's not just any point, its a hashpoint and it does not match the Déjà vu rules.

This is a retrohash but at a location with a preexisting report for an expedition making it tricky to document. It would be handy to have a ribbon template for this eventuality which added the appropriate categories and links without breaking the original expedition report. On the retrohash page, it should allow multiple ribbons with different dates and coordinates in case this happened more than once.

I'd suggest ...

An approximate ten metre distance rule for this to count (a good story beats an exact measurement).
You must not have planned or aimed for the retrohash. (If you did, it's just a normal retro expedition.)
For hashpoints which, by chance, you'd pass almost every day, you can only claim the first one.
You can only claim for your own expedition hashpoints, not every retrohash in history.
You can claim if you reach a hashpoint which you failed to reach earlier. Perhaps the lake froze over so now you accidentally got there.

Possible ribbon wording ...

Sourcerer earned the Strange attractor achievement by accidentally reaching 2012-08-08 52 0 while aiming for 2015-06-29 52 0.

And finally, if this proposal is not accepted, how do you add a retrohash to a preexisting expedition report? --Sourcerer (talk) 05:33, 2 July 2015 (EDT)