I will explain how to change imei on some android china sets only useing your fingers... Nocable No box ....
Step 1. Put double sim in phone and power on the set.
Step 2. After phone power on dial *#*#3646633#*#* .
Step 3. A menu will appear on screen , then select GPRS.
Step 4. to change imei 1 select 1ST PDP and input new imei and select ok.
Step 5. After this action in order first select "Attached" , second select "Deattached" and all will be done.
P.S. if need to change second imei just follow the same steps, only the difference is on step 4 select 2ND PDP and thats it.