Wired efficiently with a couple of separate circuits (say left and right of the room) it shouldn't have caused any breaker problems.
Maybe explains the mix of colours.. One style of faceplates on one breaker (or phase if they've used more than one phase in that lot!), another on a different breaker... Helps if your local supply is prone to dropping a phase or two and you can quickly tell which one(s) are still operating and move plugs across.
