Its NOT a fatal clash but the functionality of the 2 plugins is not compatible
admin-management-xtended allows you to quick edit author in the posts or pages list with co-authors-plus the ability is gone in quick-edit and one has to edit the post itself rather than the quick edit operations on the meta data
http://wordpress.org/extend/plugins/co-authors-plus/
Thanks for the report. Co-Authors Plus actually removes the quick edit author on the posts and pages list, so I don't believe Admin Management Xtended has any problems with it in this regard.
well that explains a lot - I had not dug into the source of either plugin
shame, because its often more convenient to edit the author etc. as metadata as a quick edit than dig into and edit the post/page especially when there are multiple posts to update.
I've added this as a feature request on Github. Hopefully we'll include it in an upcoming release.