Is it true that this time both group pass percentage is 3.5%

Yes  

around 1300 students only paased both groups 

remaining 2900 students passed either group1 or 2

students appeared for both groups -36768

cleared-4256(either both or one group).

Details are for both groups appeared 

Out of 7192 candidates qualified as CAs by virtue of nov 2016 result

1270+ were both groups passed students 

5900+ were from single group passed students who earlier passed in other group 

that means out of group 1 (2655) passed and group 2 (4545) passed 5900 students are now Chartered accountants