Mystery smoke when in a lash up?

Since in lash up it sets the speed for both, how can I avoid them "fighting" each other?  Could I set them on parallel tracks, in their respective positions for the lash up, start them and see if one is actually faster than the other?

And lastly, would it make any difference that one is a Railking, and the other is a Premier?

Thanks in advance...

You could put them on parallel tracks however why not just  a few inches apart and see if they'll  run at approx. the same speed... It should not  matter whether the engines are RK or premier. MTH has   a formula figured out that is part of the engines sound file and all MTH engines should run at the same Scale miles per hour.    Most of them do but  not always.. Don't run them in a  lash-up  if the speed are not  exactly the same  or really close.

I don't know what to think about the smoke, hope it's coming from the smoke unit.

When I make a lashup, the smoke units are turned on. Lashup ignores the single unit settings. It's like putting a new engine on the track.

The smoke coming out of everything but the smoke stack sounds like a similar issue I have seen which is why I keep a can of compressed air around. Some type of air pocket happens in the smoke unit and it needs broken up.  

I double checked the smoke setting for the individual engine itself, delegates the lash up, then re made it, and ensured smoke was off. 1 lap around, no smoke. 

However, my Railking is a tad bit faster than then the premier (started off with about 4" between them, and it caught the first one in about 16').

Is there any way to correct this? Would you still run the lash up?

There is a procedure about lash-ups described in the 'DCS handbook' you were reading. It gives some general guide lines for what is acceptable in terms of speed matching the units used for the lash-up, before attempting the lash-up. 

Basically you put both engines (as separate units) on the track so many inches apart and run them as you did above. If they don't shorten the gap between themselves more than a certain amount in a certain distance you should be good. I don't recall any of the measurements without looking them up. I don't do lash-ups very often. The book has the distance guide lines.