Thanks Joanne. A very useful post. You of all people should understand (having performed the experiment yourself) how important it is to dispell any doubts we may have in our own mind as to the efficacy of what we are doing.
I needed to know one way or the other. It was just a very strange coincidence that they happened to be exactly the same colour!
You are right that this should be widely known. I wonder if it is possible to put it in the Flush document itself. That would be one sure way to put the debate to rest once and for all.