How do I import multiple dashboard files?
How do I import multiple dashboard files? You can import multiple dashboards through the use of .ado files.
Additional Information An .adb file only contains one dashboard, a .ado file would contain the contents of a whole dockable. Exporting all dashboard files is possible. Instead of exporting the .adb files, you need to export the whole dockable. Go to View–>Dockable Manager (refer to image below): 
Then right click on the dashboard manager and select Export… (see below).
To get the dockable back in, use File–>Import and select the .ado file (see below).
Note that in a work space you cannot have more than one dockable with the same name, so you may need to remove or rename the existing dashboard manager if present. You also do this via the dockable manager by selecting properties from the pop-up menu.