As of today, 20th February, when there are several people within your agency who post to your Facebook page you can now see who has done what.
Here are the full details from Facebook:
On a Page post, the name of the person who posted will be listed below the name of your Page next to Posted by. On a Page comment, the name of the person who commented will be listed below the comment next to Commented on by. Keep in mind that only people who help manage your Page can see this information.
You can also see who posted or scheduled posts in your Page’s activity log. Learn how to remove yourself or another person who has a role on your Page.
Note: This information will only be visible on posts or comments created on or after February 20, 2014. This feature isn’t available to everyone right now.