@Mouse - Congratulations on the new Rachio and welcome to the community.
I could be that there are eight zones. Are there eight (probably round green) valve spread out over your yard for the different solenoids/zones?
I’d probably take one wire out of each of those three zones that are double and quickly run the zones noting where the system is watering. Then do the same process with the wires that were left out in the first step.
If different areas water, then I’d put each wire into it’s own zone on the Rachio.
If the same area is watered, then you can keep the wires doubled on the Rachio.
The wires look the normal size (gauge) so I don’t think they would have used two wires to carry enough current to activate the solenoid. So if nothing waters in the two steps above, they used the two wires to carry more current. Are the runs to those three zone very long?