Religion has increasingly been a theme on Game of Thrones, with the Faith Militant taking over in King's Landing and Red priestess Melisandre growing to increasing prominence over the years. In Season 6 she demonstrated heretofore unseen powers by resurrecting Jon Snow and also by revealing herself to be centuries older than anticipated. It's certainly making the religion of R'hllor pretty convincing if genuine magic is part of the deal. As the religious factions of the series become more important, they also expand to introduce new concepts and characters. One such new character is another Red priestess, Kinvara, who bears more than a passing resemblance to Melisandre. Do Kinvara and Melisandre know each other on Game of Thrones?
Neither has ever mentioned the other onscreen, but even without anything explicitly linking them together, it certainly feels like they have a connection. In addition to following the same god and serving the same religious order, it looks like they shop at the same stores; Kinvara and Melisandre not only wear very similar deep red robes, but they have identical necklaces. It's possible the Lord of Light just enforces a really strict dress code, but the show could also be visually linking the women in viewers' minds because they're more deeply connected. The books are unfortunately no help in this regard, as Kinvara has not appeared in them yet.
It seems likely that both Kinvara and Melisandre originally come from the same place, Asshai. The design of their necklaces reflects that, as that hexagonal pattern has been used to indicate some is from Asshai in the past. A shadowbinder named Quaithe who Jorah met in Qarth had a mask and clothing with a very similar pattern and also hailed from Asshai. The same pattern was also seen on another Red Priestess, glimpsed briefly by Tyrion and Varys in "High Sparrow" (Season 5, Episode 3), though she lacked the distinctive necklace.
If these common fashion choices all indicate that these characters come from the same place, then it is possible that Kinvara and Melisandre know each other. While saying two people from the same country know each other is like saying everyone in New York City is on a first name basis, they are also high-ranking members of the same religious order. This makes the probability go up a little bit.
It would also be pertinent to point out that Melisandre is hundreds of years old, and there's no indication just how old Kinvara is. They might have had centuries in which to cross paths; the real depth of their history is unknown for now. So while fans don't know yet if Melisandre and Kinvara have been introduced to one another, it wouldn't be the most unbelievable thing to happen on Game of Thrones.