@Alainn I am almost certain that they are different artists. Everything I have heard by him has been experimental/improv/contemporary jazz/classical/whatever. Basically what you would expect from Tzadik.
Not so many options to listen here, but I can recommend anyone who likes Feldman to listen to the duo album with Satoko Fujii, available here on last fm. Reminds a bit of his duo-albums with Sylvie Courvoisier, but with a somewhat different flavor.