One thing you can try is to remove all the phone entries, then re-install one. While they have the same name, they may not be full copies of each other.

What do you mean by "remove phone entry" and "reinstall one"? How do I do this? Thanks.

Yannbane,

Please file a Bug report about that issue. I suspect that Sync is synchronizing some data twice to your desktop / laptop device.

https://bugzilla.mozilla.org/
https://developer.mozilla.org/en/Bug_writing_guidelines

Make sure you add that image as an attachment to your Bug report.