Greenhouse CRM's Events iOS Application is a great way to collect prospect information en masse very quickly. It is possible that those applying through the Events iOS Application are already in your system as candidates or prospects on jobs.
If your organization has auto-merge enabled, prospects added through the Events iOS App are automatically assessed against your current system to find existing profiles with the same email address. If an exact match is found, the prospect application will be merged and appended to their existing profile.
Note: Please see here for examples where Greenhouse Recruiting will not auto-merge prospects added through the Events iOS Application.