The version I had was the re-released version (2012) which I acquired from Steam so I cannot comment on the original game released in 1995. Regardless you are probably right about this, although it would be great if someone could find more information about the original creator of these sound files.
I recently purchased a copy of Escape from the Pit out of curiosity and one thing that struck me was that most of the sound effects seem like they were ripped directly from Infinity Engine games. The Icewind Dale series, to be more precise. I don't think there is any relation between the creator of this franchise and the IE games, does anyone know why this is the case?