Where can i find the keyless entry code for a 2006 mitsubishi lancer Glx model?

I recently bought a used 2006 mitsubishi lancer. Its comes with 2 keyless entry remotes. On one of the keys the remote is not working so i have to lock and unlock the doors manually. In the second key - the previous owner opened the key and lost the sensor. Can i use the keyless entry remote from the second key and place it in the first key? Do i need to do any programming for that?|||with proof of ownership and the VIN # go to the dealer,they can solve your problem.