The audio is stereo PCM, but Pro Logic is surround sound encoding in a stereo sound track. Dolby Digital like that on a DVD requires discrete multi channel encoding, which the Netflix movies do not contain.
But Pro Logic can, and usually is, mixed in to the sound tracks of movie's stereo sound tracks.
Pro Logic encoding uses an audio phase shift to create the rear channel. The technique is not something that affects normal stereo playback.
"When a Dolby Surround soundtrack is produced, four channels of audio informationÃ¢â‚¬â€Left, Center, Right, and Mono surroundÃ¢â‚¬â€are matrix-encoded onto two audio tracks."