CAOS adds a modified version of the Google Analytics tracking code to your header or footer, depending on your settings. If you're getting this notification (or optimization suggestion) this means that besides the GA tracking code added by CAOS, you're also loading a second tracking code somewhere else in your blog. Possibly in your theme's options or by another Google Analytics plugin. Remove/disable this and you're good to go.
If you want to keep using the plugin adding the other tracking code, then enable CAOS' compatibility mode under Advanced Settings.