The PRL should be a perfect white and a pure red. I can't see any in your picture that aren't an orangey red but they do all look to have a very high quality white. The difference between the orangey red and pure red can be quite suttle with good quality CRS like yours and may not show well on photos?
As they are mixed already there is probably little point in you fixating on it as you would be better just thinking you have 'high quality' CRS and leave it at that. The grades and patterns are the same for both types so that won't help you identify them either and I am pretty sure they must have originated from the same originals as well.
Attached you can see a PRL, the red is very pure and the white very clean and bright white,