Hi Trainman (a first name would be more friendly)
A warm welcome to this great forum.
The Märklin power control stick 322979 is made of three parts:
- the battery operated control stick
- the connecting track ("Base Station Track")
- the power supply 18 VDC, 13 VA #66201

What you can't do is to connect electrically two sets of connecting track + power supply.
Why?
The connecting track is converting the infra-red signal it receives into a digital signal. All this electronics is powered by the power supply
Connecting two sets would create a short circuit between the two digital power sources.

What you can do (I think) is to use two battery operated control sticks and ONE set of connecting track + power supply.
There is enough power to run two trains but not more.

This is based on the fact that the control sticks sends IR signal only when a knob is operated or a push button is pressed.
Of course, each control stick must have a different address (1 , 2, 3, 4 set by the switch under the unit.
Of course changing the address on one of the control sticks MUST also have an address change in the corresponding loco
1= 78
2= 72
3= 60
4= 24

Note: I have not done it myself so better check.
How to change the address on your loco with the control stick?
- leave only one loco on the track
- set the switch under the control stick to the desired position
- remove the power
- push the direction change on your control stick
- plug the power again and after a short while, you may cease pushing on the direction change button
- the base station will blink red while programming
- finished, you may install the other loco too andf switch on the other control stick
- have fun

Here is the Märklin video in German, source of my explainations

Cheers
Jean

Edited by user 26 October 2023 19:18:24(UTC)  | Reason: Addition on loco address change

Hi both,

Thank you for the responses.
It makes sense, of course, that two power supplies on the same circuit won't work.

In the meantime I've also received a response from Marklin:
They say that I should definitely not have two track pieces in the same layout. But they confirm that it is possible to have two controllers send signals to the same receiver. If two controllers' signals arrive at the same time they may not be accepted. However, in practice, this should rarely be the case.

I will go ahead with this setup and share my experiences.

Steve