There is currently a few different versions of AOChat.php in use for BeBot.

One is the most current version in 0.3 (trunk) svn which is the latest official library adapted to work on php 4 but without the new queue Auno added.
0.2 uses yet a slightly different one to avoid the changes in output made by Auno's very latest version to preserve backwards compactibility of modules as much as possible.

Ontop of that there are some older versions of the library from earlier 0.2 release aswell as Xenixa's modified one.