Latest build: one camera or two?

[ssmdiy]

OK, maybe this is a stupid question - chalk it up to my newness at this.

In the latest build by Daniel do we use one camera or two? I'd like to scan one page per image and do it as fast as I can - so that seems to require two cameras.

So looking at Daniel's build I see one bicycle trigger mechanism (brilliant idea btw). Does it mean I require two for two cameras? Or I need a USB-type trigger mechanism?

Thanks very much. And I must say you guys are fabulous.
Shankha

[ssmdiy]

OK, never mind. I found Daniel's video of the build and I can see that there are two cameras.