[koujaku]

StereoKit and MRTK are currently part of the same team, so these people are my co-workers! :) We swap techniques, code, share design docs, etc. StereoKit joined the MR Middleware team towards the start of this year, and over time you'll likely see StereoKit move much closer to the Microsoft MRDL (Mixed Reality Design Language) and pick up similar features.

[jayzhan]

why build two toolkits that are similar?

[jayd16]

MRTK is more of a library. This seems like a stand alone engine.