I am running Thunderbird 24.4.0 on Windows 7. I have had the Google contacts Add On installed and activated for a while with no issues, but in the past month+ all of a sudden I am finding thousands (like 12,000) duplicates are certain contacts. It is usually a new to my system email address, and in at least two of the cases is a contact I already have in the system. And it's random - not EVERY new email address does this. I have searched and searched and found others with the issue, but no real solution or explanation of where the problem might be coming from. Google contacts? Thunderbird? The add-on? Anyone have any ideas? I know how to delete the multiples and use the merge function on Google -- but the problem is how to prevent it from happening! Not only is it annoying to have 15,000 of the same contact, but it causes terrible, terrible slowness in the auto-entering of addresses when I am writing an email, since the system has to search through so many contacts. Incredibly annoying. Thanks in advance for the help!