Are you sure that the duplicates are not the ones that you imported before without the pictures? I have not seen it create duplicates before. I would not suggest syncing the tables and files as I could see issues with the question finding the picture. Why not just sort the questions by creation date or something similar in the database and then delete out the duplicates?
Effectively the export import process is not a backup restore process.
Your synchro is more like running moodle on multiple servers.
Thanks to all of you for giving reply, so I checked numbers of time because I beleived I am doing something wrong thats why I am giving reply little late but error is same for that I am pasting here the video of that work Kindly let me know where I am doing the wrong
If you are importing the same questions for synchronization purposes you need to delete the existing questions before importing the replacements. Excellent idea to illustrate with a video.