It could be coincidence - it has happened a lot before in who.

Victorian Gwenyth looks like Gwen.

Martha Jones is the spitting image of her cousin!

And the 6th Doctor looks like Commander Maxil.

Be a bit of a large coincidence for them to all have the same name as well as being identical in appearance and for at least two of them to say exactly the same obscure phrase to the same time-travelling alien whilst battling extra-terrestrial threats.

The second one has a clear genetic connection, the first was eventually explained as a genetic connection, and the third could be a common occurrence for all we know.

Moffat is not going to base the entire arc of this season (well, half season) on a coincidence. We're not going to arrive at the Field of Trenzalore with the Doctor stepping out of the TARDIS saying, "Hmm. Well I guess the whole Clara thing turned out to be nothing at all. And here I said she's impossible. Live and learn."