Two kyber crystals linked by the Force were known as twin kyber crystals. Gella Nattai, a Jedi Wayseeker, possessed two lightsabers that contained twin kyber crystals. After Axel Greylark pilfered one of the lightsabers, Gella utilized the connection between the crystals to sense its crystal and locate Axel on Dalna.
The idea of twin kyber crystals initially appeared in the 2023 novel Cataclysm from The High Republic series, with the crystals found in Gella Nattai's lightsabers; these lightsabers were initially referenced in The High Republic: Convergence.