Is it even appropriate to call this machine a trencher? And if it is, it's the weirdest one I've ever seen. It looks like it had a John Deere combine harvester's body, the tracks of a 20-30 ton excavator, and the boom of a pipe layer for some kind of conveyor belt.
Wheel trenchers have been in use since the early 1900's. I ran a Cleveland 300 many years ago. I don't know who made the ones in your photo. I have never seen a narrow one followed by a bigger one like they are doing in the photo. I guess it would speed up the feet per hour they excavate. The ones in your photo look like they are Barber Green's.
Wheels with mean ol carbide rock teeth are about the only thing that will make it in some soil here.
If you were an underground company before the 80s in the southwest Cleveland 300s and 400s were your tool of choice all were wheel trenchers the only thing that slowed them down was solid rock then excavators came on the scene hot and heavy Its interesting here now on a couple jobs excavators have taken a backseat to rock saws now those things are mean