BI Publisher Exel Output is Aggregating Multiple Values in Single Field

The output from one of our custom BI Publisher reports is sometimes aggregating two values into the same column on more than one column.

The values can sometimes be different values. It is like a ListAGG function has been applied, so instead of multiple rows, it is aggregating the values.

This report has multiple data sets - all of them joining back to a main data set that is returning basic person record info.

Is this normal functionality - where one of your data sets represented in the Excel output returns multiple rows, so they end up displaying as aggregated values?