Do you even science bro?

Clones would not have identical fingerprints because they develop in utero and are not genetic material.

On a side note, the plural of sestra is sestry, not sestras.

Fingerprints are not as unique as was once believed.

I spoke to someone recently who had the same fingerprints/close enough to being the same fingerprints as a sibling that apparently they had considered it a bit of a parlor game to have compared ridges and whorls as children.

There was also a case of someone being detained as being on the terror watch list a few years back because they were trying to fly on a passport with the same biometrics as said terrorist....

No matter how unique you might think you are in the world, by the time your sample set rises to all of the millions of people in the world, there are bound to be natural dopplegangers, lol.

But... I forgot...

... What was your point about the single marked science blunder on Orphan Black?!? That you "science" so well that you've never made any similar mistakes (I mean, get real, the creators needed a reason for Sarah to be in jeopardy of being mistaken for Katja Obinger, so they made their fingerprints the same, which was a silly blunder, but not even remotely as silly as giving the Toronto P.D. access to advanced biometric programs that would have "immediately" tipped everyone off to the kind of programming the C.I.A. and NSA use to... still kill the wrong people using drones on a regular basis... even though the "perfect accuracy" of such programs is the basis of almost every current cop drama out there (but I'm sure you buy into that little bit of handwavium, lol, on a regular basis on old episodes of Castle or the like).

I'm not trying to get in your face (well, I am, but I'm trying to be gentle about the fact that the writers only used that particular science blunder for a very few episodes, then they moved on to science stuff that's definitely not of the no-sh!t Sherlock variety)....

Because what I'm really trying to say is that I, too, was a pedant as a teenager and used to correct friends' grammar all the time, and then I got a bit of life experience and learned that people make mistakes that become part of their own personal vocabulary and are much more personal and identifying than a fingerprint, so that the differences between Helena's use of the word, "sestra" and Sarah's adoption of it to refer to all of the "clone club" (because mostly feral Helena can hardly have been expected to have been as "educated" in the formation of plurals in Ukranian as you seem to consider yourself, and Sarah, having been raised for her formative years in England, would naturally choose to add the letter "s" to form the plural instead of whatever rule you think she violated....