Mine engages DPL, too, so that must be the default for 2.0 mono movies.
Well, the reason why it defaults to Pro Logic or PLII is because it SENSES a two-channel mix, and in the case of 2.0 Mono, it "sees" the two channels as the same and sums it into the center...
Yup. I don’t know anyone would prefer the mono sound going to the two front speakers for a video program or movie – you must run with a different crowd than I do. 
Oh, no -- I didn't mean I KNEW a lot of people who did this -- I meant that I've read online and elsewhere that as soon as a DVD box proclaims "TWO CHANNEL!! TWO CHANNEL!!" even if it's TWO CHANNEL MONO, they automatically want to use TWO speakers....
Yes, yes, yes, yes, yes.
I guess the answer is yes then.....yes? LOL.
It doesn't bother you that all the audio comes from the front center soundstage on these discs? Can you give me an idea of some of the titles you watch in this mode?