Tapping on the "Email Captures" button on CleanUpDupes app's home screen will display a list of the new contacts to review. If the contact is flagged as "New info.", then it is a contact that does not currently reside in your contact list. All other signature captures contain new information found for existing contacts.
If you wish to select multiple at once, press and hold for 5 seconds on any captured email signature. Following that, now you will be able to select all or select multiple. Once you have selected the contacts, you can press "Ignore" or "Save" at the bottom of the screen to take action on those contacts.
If you wish to review the captured signatures one at a time, press on a contact to review it. For existing contacts, the new information captured is highlighted and presented with information you already have for that contact.
Buttons at the bottom allow you to "Ignore" or "Save" the changes/new contact.