I'm planning on buying a digital piano.
Is there any way to check if a digital piano has the double escapement?
It's a feature I'd like to have. If I can't know that in advance I'll have to check for it myself.
I have to say, that if you're an experienced pianist you should go play the keyboards of interest and pick one that fits your style. If you're not, "find a friend" who is and have them help you pick. The actual mechanical implementation should matter less than the functional "feel" itself.
"Double escapement" permits a note to be repeated even if the key had not yet risen to its maximum vertical position. For acoustic piano, first proposed in 1821 by Sébastien Érard.
I think this probably could be tested by pressing the same key many times in rapid succession, also by a non player. Best it would be to experiment with some lower end keyboard without this feature first.