Avatars Plugin

While installing Avatars plugin, I noticed that the file options-discussion.php is part of the files to install.

This files already exists in the folder wp-admin and I think it was put there as part of the WPMU installation (not sure, but going by the date). The files differ in size. Which one should I use?

Further, I have uploaded an avatar and cropped it. When browsing to a a previously created post on theme edu-clean, it still shows the default 16x16 mystery man avatar and not the newly uploaded. Would it be because of the file above or something else ? (update: I just substituded the options-discussion.php and nothing)