Mirror iPad camera to two projectors (simultaneously)
As other commenters have already said, it doesn't seem to be possible to AirPlay a display to two targets at once. 

Option 1)

The best solution I can think of would be to run something like AirServer on a Mac or PC. Attach the computer to both projectors and have it mirror the display. AirServer will make the computer a valid AirPlay target and you'll be able to mirror your iPad's display to it (and thus see it on both projectors simultaneously). 

Option 2)

You could also buy an HDMI splitter and two long HDMI cables. That way you could AirPlay your iPad's screen to an Apple TV and have the Apple TV output to both projectors simultaneously. 

Option 3)

I believe it's also possible to connect some projectors to a network (eg: via Ethernet or Wi-Fi), so perhaps you could look into that? You may be able to create an AirPlay endpoint on your network (perhaps with a tool like the aforementioned AirServer) and then direct its output to your network-connected projectors. 

Option 4)

You could browse the App Store for an app which streams camera input from an iOS device to the network. You could essentially turn the iPad into a streaming HTTP server and then have any number of devices tune into it. Then you could attach an iPad, iPhone, Apple TV, computer (or anything, really) to each projector and have them stream from the source iPad (eg: By visiting the URL for the source iPad's stream in a web browser like Safari or a video player like VLC). This has the advantage of not requiring any long cables, although you'd need a solid Wi-Fi connection.