Interesting split guitar effect?

I heard a soundtrack that used an acoustic guitar in a finger pick style. The guitar was split L and R and although it was wider, it still was just the single guitar. What was interesting is that the higher notes (E B and G strings) were heard panned left and the lower strings (D on down) were heard panned right. So how was this done? What I can think is that they cloned the tracks and used a high pass filter on one and low pass filter on the other panning left and right. What do you think?

What I can think is that they cloned the tracks and used a high pass filter on one and low pass filter on the other panning left and right.

That'd be one good way to do it. There are a couple of EQ effects in a Lexicon MPX-1 that will allow you to do this in a single track. A mono signal is split; lowpass on the left, and highpass to the right. 'Fc Splitter' has independent control over each side's corner frequency, whereas 'Crossover' has a single shared corner frequency.

Using a 'virtual' acoustic guitar (How's that for an oxymoron?), you could accomplish a similar effect with keyboard splits and/or pan keytracking.

i attempt effects like this all the time, and the best way i do it is just to record 2 separate tracks, one playing high strings another playing low. though it may not give the true sound of one person playing, it does sound nice.
how do you know it was a single guitar?

Midi-Guitars can do that,..
I think Brandon once mentioned a guitar with split outputs for each string.. don't remember which one it was though..
also Voxengos Soniformer has a frequency-dependent-pan-option.. you might want to try the demo..