I have the ez command dcc set up am I able to have the dcc engine idling while I operate the dc engine and vice versa?
You can not have a DC engine sit on DCC track for very long or it will burn up the motor. You can have a DCC engine sit however without burning up.
To protect the dc engine I would park it on an isolated siding and use a toggle switch to apply power only when you are going to operate it. For the readons stated above dc engines should never be left idling on a dcc layout.