Often when configuring markers you will need a "reverse" marker that displays when the metadata in a certain field has changed. Cloning markers is an easy way to achieve this.
In the Markers node on the Workflows tab in the configuration there is a row of icons to the far right for every marker you have made. To clone a marker you click on the first icon with the green arrow. The cloned marker will be added to the bottom of the list, and you can easily modify it by clicking on the Edit button (the middle one of the three) and change the settings for the marker as needed.