To duplicate a calculation, click the calculation name in the report:
The calculation builder opens.
Click Duplicate in the bottom right.
A new calculation with (copy) appended to the name is added.
From here, you can edit information, components, formulas, filtering, and operation.
Once you are happy with your changes, click Save at the bottom right to add the new calculation to your report.
To cancel without saving, click the X at the top right of the builder. The new calculation will be discarded.