What you are doing is processing data from a physical Node that creates data Inputs, to a storage Feed. There does not need to be a direct correlation between the Input structure and the Feed structure. If you have 2 inputs that both produce temp & humidity, you might want a feed group of the 2 humidity data streams and another group of the 2 temperature data streams.
The Feed names need to be unique. I am not infront of a system right now, but there are 2 parts to the Feed; the first part is the grouping and the second the feed name. I think the unique bit is a combination of the 2.