How did they get 'the stereo treatment'?

X-Y, ORTF, stereo mic, etc?

Or was one mic recorded to a stereo track?

(And BTW, how does this correlate to "sample types"?)

The mic was recorded to a stereo track. Sample type as in stereo or mono.

kupon wrote: The mic was recorded to a stereo track. Sample type as in stereo or mono.

Like most of us, you may have 4 GB worth of Stereo vocals.
Are they in wav or in the format of the DAW program?
Either way, highlight the track, then click on seperate Stereo track.
Now you have to decide on whether to pan L or R either of the now serperate vocals. The first thing to do though is to move one of the tracks back or forward by only a few milli seconds. It could sound like John Lennon delay when you do that.

The mic was recorded to a stereo track.

For what purpose?
One mic, one source?
Convert the file(s) to mono, most DAWs can do it with one click or selection in a drop down menu.

Filmmusic sez:

Like most of us, you may have 4 GB worth of Stereo vocals.

That's just not true.
If we are going to make generalizations here I'm gonna go out on a limb and say that most of "us" have been recording one (mono) source to one (mono) track since the days of magnetic tape, and have continued to do so as we've switched over to the digital realm. Wasting HD space on stereo tracks of mono sources is a foolish thing to do.

Thanks everyone for your responses! Truly appreciated!