I see no problem with it. Each controller is specifically linked to each aircraft. I've never done it but I would not think it a good idea for the pilots to stand right next to each other, though. No dogfighting, you guys! Somebody will lose an eye!
Done just that that last week, and the only abnormality i've encountered is that i lost the telemetry from the Standard whenever the Advanced came too close. It was probably because the Advanced uses 2.4GHz for both telemetry and control and the Standard also for its telemetry transmission.
Anyway, here is a little video i took with my Advanced from the flying Standard.