The 'data consistency check' brakes one of two surveys by renaming the survey and token table and then offering to delete the inactive survey:

Data redundancy check
The redundancy check looks for tables leftover after deactivating a survey. You can delete these if you no longer require them.
The following old survey response tables exist and may be deleted if no longer required:
Survey ID 395136 saved at 20 Dec 2012 09:22 containing 3 record(s) (responses)

The survey still shows up as active in the admin console but if you try to run it the following message appears:

Internal Server Error
The table "{{survey_395136}}" for active record class "Survey_dynamic" cannot be found in the database.