http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31891&start=0

JTable or JModelAdmin seem to reparse JSON strings. This leads to the string to seemingly duplicate. The JSON code is held in a hidden form element and built with javascript so it can be parsed with the form with no modification to the save function of JModelAdmin or JTable. Looking at the code directly I see nothing that seems to reparse JSON, and no plugin that seems to do anything with JSON (all install defaults).
I have pinned the blame on my own code, positive I may just be missing something and this is not a bug, however after hours of going through the execution of my code from beginning to end I do not even encode/decode the JSON at all, as that is handled by Javascript and not PHP in my component.
First save is usually fine if there is a physical change from the last one when it is saved it does not do it, however right after the save if you save again it will duplicate.
If any clarification is needed I will be happy to provide it. If this cannot be reproduced then I will list all core plugins that were included in my install and see if there is any difference.