Harold,
Just go ahead and add them to the remote. DCS will assign each a different ID#. However, they will be assigned the same name. Regardless, they will respond to commands as two different engines, which they are.
If you want to make the names different, just give one a Custom Name.
This and a whole lot more is all in "The DCS O Gauge Companion 2nd Edition", now available for purchase as an eBook or a printed book from MTH's web store site! Click on the link below to go to MTH's web page for the book!