to Delete the duplicate Dashboard in AccessPoint, find the distribution folder and delete or move the duplicate qvw files in there, It is possible that the files is in different folders, you will have to look if you have many distributionfolders in QMC. The timestamp on the file will give you information when it was latest reload.
Before you delete/move the file, have a look that no DocumentCals is allocated to the document.
Otherwise you will create a "ghostcopy" that holds CALS, but no longer exists.
When you have release CALS from the document and delete/move the file, just open the task and delete it.