What exactly is the "double" in double escapement?

iternabe

Google's AI answer:

It's called a "double escapement" because it allows the hammer to "escape" (fall back) and then be reset by a second, partial "escape" action (via a repetition lever and spring) before the key returns fully to its resting position, enabling much faster repetition of a single note than the original single escapement mechanism. This innovation by Sébastien Érard in the 1800s is fundamental to modern grand pianos.

However, I could not find those exact words in any of the referred links in the AI answer. Today, I am rewatching Robert Grijalva's very detailed YT video explanation of How a Grand Piano Action Works (at 14:20 mark), and noticed his explanation:

... as the repetition is traversing upward, the jack tender and the heel of the repetition lever arrives simultaneously at their respective adjustment screws - the drop screw here and the let off button here - this simultaneous feature is the reason for the title double escapement

Which explanation of the meaning of "double" is the definitive one?

iternabe

Here is an illustration to help with understanding Grijalva's explanation: the simultaneous "double" contacts made to trigger the escapement are:

Repetition lever and Drop screw
Jack and Regulating screw

MRC

Grijalva certainly knows how the mechanism works.

With regard to the terminology, however, I have always understood "double escapement" in the sense presented in the AI answer you posted.

CrisOliveira

As far as I understand, it's a double escapement because there are two points of contact forcing the escapement, not because there are two instances of escapement. Robert Grijalva is correct, I think. The repetition mechanism calls for a second point of contact, hence the name.

I may be wrong, but I don't trust LLM AIs. They work by putting together sentences that sound plausible, but there's no guarantee they are correct. Even if the AI is correct this time, that fact ruins it for me.