UA: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.2; WOW64; .NET CLR 2.0.50727; WinFX RunTime 3.0.50727; .NET CLR 1.1.4322) As shown on the URL (a search for "ChatZilla"), the expanded details for ChatZilla only list 1 author when there are 4 - all 4 appear if you click through to the real details page. This is misleading information, at best, plain wrong at worst. If you don't *want* to show them all, for clarity or space, it really should indicate that there are more authors not listed, perhaps by "Author1, ..." or "Author1 (and others)" so such.
This was fixed in trunk (SVN r2280). When more than 2 are present, "others" is shown as the third and linked to the details page.
Interesting; the URL of this bug is showing all 4 authors currently. Did something change after r2280?
In fact, the limit of 2 users max wasn't properly used. I fixed this also, SVN r2309. Won't be on preview though until the next push.
V.FIXED on preview.addons.mozilla.org.