Duplicate Signatures
The main reason a User may have duplicate signatures is that they probably have a signature still enabled/turned on within one of their email clients (laptop, phone, tablet, etc). Have the User verify that all signatures have been disabled/turned off on all devices.
If the User does not have signature enabled on another device, you can remove and re-add the User to the Black Pearl Mail App. Be sure to capture all the Users information before deleting.