Doesn't the German version also have the music in the garbage pit scene? That too was deleted when they remixed it for the SE, from what I've heard.

Your theory seems likely, that somebody thought it was an error for the scene to have music, not realizing that some foreign dubs actually were made that way originally; either that or they just didn't think it should be there when it wasn't in the English versions. So they swapped it out from an alternate source: possibly not noticing the difference in voice/dialect, or possibly just not caring.

I don't know the exact times when the various dubs would have been made, but given the facts, this seems the most likely explanation.