Indeed, and with the work done by Guix and the Reproducible Builds project we do have a real-world example of diverse double compilation which is not just a toy example utilizing the GNU Mes C compiler.
Projects like GNU Mes are part of the Bootstrappable Builds effort[0]. Another great achievement in that area is the live-bootstrap project, which has automated a build pipeline that goes from a minimal binary seed up to tinycc then gcc 4 and beyond.[1]
I feel the need to point out that the "Bootstrappable Builds" project is a working group from a Reproducible Builds project which where interested in the next step beyond reproducing binaries. Obviously this project has seen most effort from Guix :)
The GNU Mes C experiment mentioned above was also conducted during the 2019 Reproducible Builds summit in Marrakesh.
https://dwheeler.com/trusting-trust/#real-world