We observe some difference in the display of dashboards in Dashboard Management and My Dashboard. Why?
The particular User with which you have logged-in might have been present in more than one ROLE and therefore when the User logs-in, dashboards from all the ROLES under which the User is assigned to shall appear. Whereas in 'My dashboard', the dashboards that are assigned for a particular ROLE will appear. Hence there can be difference in the display of dashboards.