Checking your IMEI on a Samsung Galaxy is a little bit technical, but pretty simple.
To get the device IMEI number, simply dial the code *#06#
Your device will show you its IMEI number, It will look a little bit like this ( 354330059425938 ).
You can tell if there's something wrong if you can an IMEI number returned that looks like (000000000000000) or (004400...)
That would mean there is a technical fault with your samsung galaxy grand duos that needs repairing.