Avoid creating measure groups that have the same dimensionality and granularity
This rule analyzes whether there are multiple measure groups within a cube that contains measures that have the same dimensionality and granularity. This rule does not apply to distinct count measures.
Best Practices Recommendations
For best performance, you typically consolidate multiple measure groups that have the same dimensionality and granularity into a single measure group. However, do not consolidate measure groups that contain distinct count measures into one measure group. Instead, put each distinct count measure in its own measure group for best performance. Each distinct count measure group should have the same dimensionality and granularity as the non-distinct count measures from the same fact table.
For More Information
For more information about how to define measures and measure groups, see Defining and Configuring a Measure and Defining and Configuring a Measure Group in SQL Server Books Online.