TWO ENGINES STARTING UP @ THE SAME TIME

I assume they have different IDs.

If a wheel is off the track and causes a spark, that will sometimes trigger movement in a shut down loco.

If it happens again, change the ID of one of the locos.

How many times did it happen?

I had that happen a while ago. I was re-adding an engine and ended up with duplicate IDs. One did not respond to engine add, but was willing to start moving. All these problems are gone now that I switched to a rev L.

Mike

THIS IS A L TIU.

Do you have 2 remotes?
If an engine is on a powered down siding and the remote has the ID open, I can see this being correct operation.
Otherwise, something is odd.

Msgt Russell,
I agree, but I thought the new P3 engines eliminated this problem,
is that correct? Your home layout is great.
PCRR

This occurs when two engines have the same ID #. Having the same name will have no consequence to this issue.

I don't have the new TIU's, but I've experienced this problem in the past. I believe it was caused by weak batteries and engines ending up with the same ID numbers. This is one of the reasons I'm replacing old batteries with BCR's. I've done seven replacements so far with no regrets. I'm learning that weak batteries can cause subtle problems and having good ones,or BCR's,is important. This little quirk is interesting though, isn't it.