“Errors in the metadata manager. The ‘Report Metrics’ (some name) measure group has more than one distinct count measure.”
When you create a new measure that uses ‘Distinct Count’, Business Intelligence Development Studio (BIDS) automatically creates a new measure group for you. But when you try to change the usage of an existing measure from a group to ‘Distinct Count’ that already has another ‘Distinct Count’ defined, you get this type of error (while deploying).
After digging a little into BIDS, I found out that cube in BIDS doesn’t allow multiple measures with ‘Distinct Count’ to exist in same measure group. For query performance reasons, this behavior is not encouraged by BIDS.
So, the way around it is to create a separate measure group for each measure that implements ‘Distinct Count’.
Furthermore, if you have too many measures that require this type of usage, you can create calculated measures to avoid having too many measure groups to display in the browser. You can hide all the ‘Distinct Count’ measures and then define calculated measures for each distinct count measure. Then assign the calculated members to specific measure group that you want to.