TarasBoutiqueAtEtsy
They are not identical. However, if you know of a product called "pet fur dye" then you answered your own question.
kismetsguardian
Most cats will come when called. Why don’t you just call one and see what happens. I also agree with one of the previous answers, they aren’t identical, so maybe just get used to the different stripes each has on their face. As well I’m sure they each have their own individual personality, that should help you to tell them apart as well.
I’m not a big proponent of collars on animals. I’ve seen too many get cats get stuck on stuff and some have even died while the owner wasn’t home. So I wouldn’t recommend collars. A dab on one ear if you still can’t differentiate would be fine.
Entropy
They're not identical. Look at the 'M' on the forehead. One has taller 'humps' to the M. The other's are shorter, with the stripes coming together sooner. And seems darker from the picture. Plus the taller humped M cat seems to have a more angular face.
You could try different color COLLARS.
?
A tab of color will do.
Evie
Lovely cats. You should buy cat collars for them with identity tags.