You cannot directly ""unmerge"" two surveys once their data has been merged using the Merge Data feature. The merge process combines responses from multiple surveys into one, and there is no option to automatically separate them back into their original surveys.

If you need to distinguish the responses, you can use the external reference field, which records the original survey ID for each response after merging. This allows you to filter or identify responses from each original survey within the merged data.

Based on the external reference, you can delete that data so that you will be able to sanitize the response that was merged.