Oh I dont have pictures so I ll bump this up for you.
But to answer, yes there is some variation in shade. Its not just ageing or fading almost all of them come with 2 or 3 different shades. Now by "variations" I dont mean anything official or deliberate or even anything which is often all that different - its really the same colour but clearly when so much fabric is being produced there is some variation in finish and so you get the same bandana in supposedly the same colour but just varying a little on the spectrum of that particular colour.