It can happen that you end up with duplicate address book entries in Mozilla Thunderbird and wonder how you can remove them so that only one entry per contact is visible in the Thunderbird Address Book.
The current Thunderbird address book is most likely fragmented or corrupt, and the easiest way to fix that is to create a new Address Book and copy the contents of the old Address Book into the new one.
You should backup your Thunderbird profile before you start this process. The easiest way would be to use the software MozBackup which creates a backup of a selected profile with just a few clicks.
After the profile data has been saved you can begin the process of creating a new Address Book in Thunderbird to get rid of Duplicate Address Book entries.
You can use a Thunderbird extension instead as well, if you prefer that. Check out our review of the Thunderbird Duplicate Contact Manager extension for instructions on how to use it instead.
Instead of having to create a new address book and copy data to it from the old, you can use the extension instead to do so.
To use it, open the address book after you have installed it and select find and manage duplicates from the Tools menu there.
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