The following is regression caused by Issue #15442.

1. Open discrete-measure.vizx, and goto Worksheet 1
2. Remove Index from Rows deck
3. Change Chart Type to Bar
4. Drag and drop Profit to Columns deck
5. Drag and drop Territory to Color deck
6. Result: Stacked bar chart is rendered for both SUM(Freight) and SUM(Profit) measures, which is correct.
7. Convert SUM(Profit) in Columns deck to Discrete
8. Result: The chart is incorrectly rendered. Further, the SUM(Freight) measure is rendered 3 times per each year, which is incorrect. See incorrect.png.
9. Expected: A chart similar to correct.png should be rendered, except the "(null)" values for SUM(Profit) should be replaced with whatever the correct values are.