We can fix this issue in engineering mode.  But for that you need to keep your imei numbers ready.  
Please check your mobile box or bill or older screenshots Containing imei numbers

Process to follow :
1.Go to engineering mode *#*#3646633#*#*
2.Swipe one time left to go to connectivity menu
3.Select CDS information option > Radio information
4. Select phone 1 to set imei 1and

Here type and send this command with your imei in the place of 1s

AT+ EGMR=1,7,"111111111111111"

This will fix your imei once the command is sent successfully. For sim one.

Similarly do it for sim 2 also. Under phone 2 option.

Let me know if you want any assistance further.

If it doesn't work for sim 2 - use
AT+ EGMR=1,10,"222222222222222"
For SIM 2

It must work with that process IF fails try without space between + and E

Which is AT+EGMR=1,7,"<your IMEI here>"


IMEI should be inside the double quotes