@Gandalf
I tried changing the secondary monitor to the same resolution as the first and the display is weird with 1/3 missing and the horizontal smooshed together. The effect persisted, so this may go beyond simply the resolution and may be more of a video card issue with this particular PC.
I tried having the window overlap both screens and the result is that the game gets jittery as if it were solely on the second screen. Weird, but if I had to choose between two rates I would choose the lower of the two and that seems to be what the PC is doing.
I'll try some variations at home tonight and report the results.
Unfortunately I'm not versed in 3D commands yet so I've no clue how to code this with 3D sprites. Perhaps it will be my first project in 3D. It might be awhile since I'm working on a rail shooter project that I plan to be my first independent creation.
I'd love to be able to create a game that utilizes dual monitors some day and this will be a hurdle. Not that I'm afraid of hurdles.
@WLGfx
I thought something like that might be the case. I'm curious to see what happens with dual monitors on separate GPUs (actually crossfired, but might work separately?)...
The 3D planes that Gandalf suggest would help deal with the slower rate on the secondary monitor, or I believe that is what he thinks.
The parallax on its own doesn't seem to have an issue (probably because on its own it is direct draw to video memory). It did, however have and issue when I was using fastsync and no sync rate.
I'll check out some other games not built with DBPro and some built with. I know many have different issues, but many don't. For example, Left 4 Dead 2 I can switch to either screen at home with no issue, but Alien vs. Predator just sort of locks up.
Thanks guys, this is all quite educational and interesting.