solution:
download MTK engineering mode apk : MTK engineering mode apk
install and open MTK engineering mode in your phone
goto connectivity > CDS information > radio information > phone 1 & phone 2
for phone 1: AT+EGMR=1,7"input your new imei no." then press Send At Command
for phone 2: AT+EGMR=1,10"input your new imei no." then press Send At Command
reboot phone
dial *#06#
download MTK engineering mode apk : MTK engineering mode apk
install and open MTK engineering mode in your phone
goto connectivity > CDS information > radio information > phone 1 & phone 2
for phone 1: AT+EGMR=1,7"input your new imei no." then press Send At Command
for phone 2: AT+EGMR=1,10"input your new imei no." then press Send At Command
reboot phone
dial *#06#