True, it's a weird thing to say. I am in no position to rank them, I assume they are both excellent at their niches (granted bellard seems to be interested in a lot of niches) but it never hurt anybody to be humble in this position.
Bellard did multiple breakthroughs: ffmpeg, qemu, tcc, jslinux, a state of the art FFT algorithm. I probable skipped a few.
With all due respect to carmack, a single ballard's projects would put anybody into the eternal hall of programmers fame right next to Linus, Carmack, Stallman, the Bell labs crowd and others.
i do understand how carmack did what he did logistically (time, effort, skills, compensation)...
Fabrice is just out of this world. When? How? Why? No idea.
https://bellard.org/pi/pi_bin.pdf
Though I have to say the last line of the proof "...which gives (1) by reordering the terms" took me much head scratching to understand!