Multiple wires can work in some cases.
It seems you don’t have to worry about it?
Was your question before about the 400w you were seeing with “99% of breakers off”? A meter alone certainly wouldn’t be registering 400w. If you are seeing that after the meter then you almost certainly have a load on the panel circuitry somewhere. Can you switch of all the breakers to confirm? Obviously where the Sense itself is plugged in would have to remain on … with only that on you should see about 2w on the main meter or in Signals but you’re probably best leaving modem/network gear on … usually that’s only going to be a few watts and easy to add up