"interlocking, the practice of taking one print and showing it on multiple screens within a theater"
Simultaneously????
Various ways to do this.
If there are multiple reels, as soon as you finish the first reel, start the second reel and start reel #1 on a second screen.
They can also reflect off mirrors onto multiple screens from a single projection booth.
Of course if it's a digital projection, stream the feed to multiple projectors at the same time.
Yep. When the Cinerama in Seattle showed Attack Of The Clones, it received the digital signal via satellite from California. The film copy wasn't even IN Seattle!
It'd be nothing for an electronic hook-up between theater screens receiving such a signal.
Even if they weren't getting it from a 'bird', if they had a digital copy, they could easily do the same thing.