Thank you all for the replies
So what I gather from everything is that we do not actually have 3 clones of the same system as this would be too heavy and a few other reasons as mentioned. This is news to me as I was of the impression that identical backup systems were in place.
Also, am I correct in now saying that all 3 systems are used continuously then in flight with the loads being split across the 3 of them and if one goes the other 2 try to pick up the mess and split it between them?