There are currently two aggregation help files - aggregation.html (long, containing typos) and aggregation2.html (very short, not explaining anything).

According to the coding guidelines http://docs.moodle.org/en/Coding

All help files should be translatable - create new texts in the "lang/en_utf8/help" directory and call them using helpbutton(). If you need to update a help file:

• with a minor change, where an old translation of the file would still make sense, then it's OK to make the change but you should notify translation AT moodle DOT org.
• for a major change you should create a new file by adding an incrementing number (eg filename2.html) so that translators can easily see it's a new version of the file. Obviously the new code and the help index files should also be modified to point to the newest versions.

Thus, if aggregation2.html is not a new version of aggregation.html, it should be named differently.