Sounds like the 2 Lionel engines have the same I.D. number. Change 1 engine to #83 and the other to #32.
Then delete the first engine in the DCS handheld. Then add the Lionel #83 to the DCS handheld, and add the #32 to the handheld.
You did not say but I take it you have the Bases connected together with the serial cable.