Add duplicate checking support

[t413]

No description provided.

[bud77]

Not relevant since SMS backup & restore can check for duplicates :)

BTW a huge thank on that script. I just spent 5 days trying to import gf's iphone's sms, and none of the different tools worked (50k messages...)

The script did the trick ... in less than 12 seconds !

Again, thanks!

[lockheed]

What do you mean "not relevant"? SMS Backup & Restore" is notorious for not being able to handle MMS restore properly (it changes MMS date received to the date of the restore), therefore can be totally useless. It would be good SMS-tools had duplicate check rather than rely on third party apps that do not work properly.