Under no circumstance would I install two different decoders in an engine. If anybody thinks he or she is saving any money, think again. The hours that will be spent
trying to make them both work together, will only end up in frustration. Then you will send it off to somebody that know how to make it work, for a price. Trying to make them work would be enough to cause anybody to get out of sound all together! That being said, friend of Dave Engle and mine gave the following comments concerning the use of dual decoders: "Generally, you would use the decoder lock feature in both decoders in the following fashion: The decoder lock is used to change CV's in only one of several decoders with the same short address (CV1) or long address (CV17 and CV18) that are installed in the same locomotive. Assign a number to CV16 in each decoder (i.e. 1 to motor decoder, 2 to sound decoder, 3 or higher to other decoders) before the decoders are installed in the locomotive. To change a value in another CVof one of the installed decoders, first write the number 1 (motor), 2 (sound) 3 or higher (other) into CV15, then send the new value to the CV to be changed. The decoders will compare CV15 to CV16 and, if the values are equal, the CV to be changed will be changed. If the values in CV15 and CV16 are different, the update will be ignored. The motion decoder has two CVs that you can set to lock the decoder so it won't listen to re-programming commands. If the DH465 follows Digitrax's standards, then CV54 set to 0 enables the Lock function and CV16 sets the lock code, (It is recommended to set the mobile decoder lock code to 1, and write down the lock code or put it in the memo section of the Roster Entry tab of Decoder Pro if you are using it). Once you have programmed the motion decoder to act in the locomotive as you want and locked it, then follow suit with the sound decoder." Keith Robinson
