wat is double v-model?
You asked a similar questions a few days ago and were provided quite a lot of information - what more are you looking for?
Also a search on the functional testing forum for v-model will results in several threads where you can get information.
I recommend that you investigate and make yourself familiar with the search function.
I have not failed. I've just found 10,000 ways that won't work" --Thomas Edison
I've seen this referred to as a "W model". You could try googling that - or search this site or Stickyminds.
W model is basically to overcome the issues or bugs which come at final production stage.So at each and every stage of development the product is tested and reviewed continously