revisions don't seem to work

today i wanted to look for an earier version of the spanish mestiza chile page (/es/content/mestiza-chile-2013-0) since there used to be more text (as is on the english & portugues versions) but it seems to have been disappeared.

so i thought, no problem, i can revert to an older version. however, all of the revisiones (/es/node/1035/revisions) appear to be exactly the same - the most recent version. i checked the english page in case i was missing something in translation, & all of the english revisions are also the same as the most recent version.

in the edit interface, "create new revision" is ticked by default, & my understanding was that this meant it would keep the previous version as the revision. maybe i have misunderstood this? but all the "revisions" have the possiblity to be reverted to ... which is a bit pointless if "create new revision" is actually copying over the old revision with the new one ... i don't understand :(