We have duplicate contacts from uploading contacts to CC. We believe CC would remove any duplicate email address, but apparently it has not. This is a huge problem since those contacts now relieve our emails more than once...(and sometimes unsubscribe!)
Suggestion: You need to add "Merge Contacts" option. Where we could merge different contacts that have the same email address, the lists they are on will also merge automatically. Exporting contacts, cleaning the file and importing back again is such a hassle specially when you have to find the lists they're on. Not something any company would enjoy.
Also, now that I'm working on cleaning our contact list. A script box pops up, and causes issues with the website. Eventually it will go back to the main page I've set before hand and NOT complete the task. I have tried stop script, continue and debug(?) but it all came back again.