When two or more Volume Regions overlap, they will all be invalid. This is displayed in Kubla Cubed by the element being highlighted in Red, with an error message of 'Validation Failed' written in the metadata field. No volumes are calculated or reported for the regions that have this status.
The valid measurements will still show in the The Measurements Panel and on the export reports/spreadsheets. The errored element(s) will not be reported. To rectify this error, either diasble one of the elements that has a duplicate region or delete it completely.