A real strange problem: is it an AC3 5.1 or AC3 2.0?

[colasonic]

I got a DVD and tried to encode it into divx. I was caught by a very strange thing. Its sound track is an AC3 2.0 384kbps. But when I watch the movie, I can confirm the soundtrack is in a 5.1 format. Dialogues comes out from the central speaker, and the other four do their respective job. I don't know how to confirm my observation. I just can use my ears, because all softwares I tried told me it's an AC3 2.0, including windvd, powerdvd, dvd2avi, nandub, soft encode. I also use vobedit to open the vob, the data says, "audio coding mode 2 Channels: 2 (2/0) (L, R) "

This DVD has only one audio track.

So, can anyone tell me if it's possible, or just my illusion?

[OvERaCiD23]

is your audio decoder using Dolby Pro Logic? this creates surround sound from a 2ch source. i would trust all those programs that verify it as a 2ch source. your decoder is turning it into surround sound (not the same as 5.1, but good enough for the casual listener).