I think you misread the page, as it says that Red Hat has 13,400 employees, which is 22x more than 600, not "almost twice" :)

But also, both numbers are also outdated. The Canonical employee count is apparently around 500 in 2020 [0] and the Red Hat employee count is no longer public post-acquisition, but it's higher than it was in 2019.

[0] https://www.phoronix.com/scan.php?page=news_item&px=Canonica...