Most Maerklin (and other) steam locos have two or three lights at the front of the loco and the same at the back of the loco or tender.
I suspect that this is not the normal prototypical arrangement on say DB or DR locos. Does anyone know what is, or was the running light arrangement used, positions and colours?
Jabez

Prior to 1955 (era3a and earlier) German locomotives only had 2 head/tail lights . After then (era 3b), 3 lights was the standard.

Prior to the change to 3 running lights, the 3rd light was only illuminated as Dale advised as a signal indicating a special service.
Models from 1954 and earlier should only have 2 headlights illuminated. Since E-loks are electric the 3rd headlight was installed/fixed as opposed to a removable light.

The problem is manufacturers have often had their era3a and earlier e-loks with all 3 lights illuminated instead of 2.
Perhaps they fear ignorant customers would complain and return them because the 3rd top light is not lit, despite the fact it should not be.
My era3a e-loks I have had to modify to turn the top light off. Mainly Marklin models. The Roco E-loks have been correct with only 2 lights illuminated.