http://fr.wikipedia.org/w/index.php?title=Neil_Armstrong&action=history shows two manual (script-assisted) reverts to the same edit, in revisions 79252172 and 79252174.
This shouldn't be possible. Either Le pro du 94 :) should have got an edit conflict, or it should have been silently skipped without getting a history entry.
This could be something serious (such as CronologyProtector not working, or the code no longer being in a transaction) or trivial (such as the js script breaking the edit atomicity).
rev_id 79252174 by Le pro du 94 :) has a rev_parent_id of 79252172 (Superjuju10 edit) which suggests a bug in our code.
The text of 79252172 and 79252174 are equal. After-the-fact editing of one doesn't override the other (as expected). Both show a rev_sha1 of o2dxb378cwej8zv7lx5y1p0wk87oduo.