That transformer can be used to power up to two trains, but it designed to control only one train at a time.
The transformer allows you to select one of four delta addresses (or digital addresses - see table)

Delta Setting=Digital Address
1=78
2=72
3=60
4=24

I am not sure what you mean by switches 1 and 2 on. For the delta decoder, you should select one of the switches only (1 through 4). I don't think that the system was intended to have more than one dipswitch selected at a time.

If you want to upgrade to more options, you can decide to upgrade to the mobile or central station or find one of the older 6021 controllers. This will allow you to access up to 80 different addresses.

I will have to check if I still have any delta loks here. Most of mine were upgraded to fx/mfx over the past few years. I do have the older delta control, so I will be able to do some experimenting over the weekend. In the interim, please select only one of the four switches so that each lok is assigned it's own address. If you want to operate two loks at the same time, please select the same address for both, but remember that both will respond at the same time. I am not sure if your controller will allow you to switch between the four delta addresses while a train is moving. This presents a risk because the train that is no longer being controlled should normally continue to follow it's last instructions while the next addressed lok will suddenly start to move at the indicated speed on the transformer. This is possible with the 6021 because once you start to key in the next address, you can lower the speed to zero so it does not start at speed.

Regards

Mike C

Hi!
It seems the overload protection of the controller gets triggered when both locos run.

Not much can be said without knowing the ref. numbers of the locos/starter sets.

Delta locos with DIP switches normally have the standard AC/DC motor and are known to draw a higher current than modern locos with DC motors. Current draw will be higher when locos are in a bad condition (collector dirty, gear with hardened oil, &c.).

That small controller AFAIK did not come in starter sets with Delta locos, so when the manual mentions running two locos at the same time they did not have Delta locos in mind.

In the manual that came with the 29130 starter set, they write the maximum output of 67025 is 0.4 A.

Manual:
(Copy URL to address field)

0.4 A should be enough to have two locos with DC motors drive slowly (and locos with light bulbs, sound, or smoke generators could be too much).
It's not enough for two locos with AC/DC motors (as those draw more current).

A stronger version of the 67025 is the Delta Control 66045 (you'll also need a real transformer instead of the power supply you have (it's not a transformer despite what's engraved on it)).

An MS2 will also give you more power - and more options. You also need the track connection box and the appropriate power supply with that option.