I prefer to imagine that great minds think alike! :) Or more scientifically speaking, the theory of multiple discovery [1].

[1] https://en.wikipedia.org/wiki/Multiple_discovery

The amount of [citation needed]s in that article is too high.

Or it's based on some paired programming hype/growth/buzz that happened months ago and both decided to implement it as an option. I mean it takes a while to implement complex feature sets like this, so maybe some trend in the industry got people in both communities trying to implement this at the same time?

It's not exactly groundbreaking. SubEthaedit did it years ago.

You put developed "the world's most advanced code collaboration experience" as advertised by the website in 48 hours ? Can I hire you somewhere ?