You are reading the dates wrong, jacksonmj's save is from September 2010 (I think the website might confuse the dates too), the Kamalu version is a November copy a few frames advanced over this specific version https://powdertoy.co.uk/Browse/View.html?ID=17758&Date=1285081596
jacksonmj's version has since been updated multiple times and shows a newer date.

EDIT: That link only works with a userscript, you can either enable the script or view the history of the save in-game.