Looking at my post again and taking into consideration Waldo's comments I have come to the conclusion I don't know from where I speak!
I think I can now see that no electrical values are being changed, a different device is merely being inserted into an existing circuit.
I do think the guts of the 12 volt flasher would be designed to react to a smaller amount of current than the six volt version and therefore would flash more rapidly.
As Waldo pointed out, I may not understand all Mr. Ohm has to say about this deal and I will admit I have never gotten a true grasp on his laws so I am probably completely soaking wet on my theory.
Stuart