Sorry Lord Flynn, the spare cockerels are penned individually. So we have one spare cockerel per breed. We tried keeping two together but Spring came; what a mess! Uses up a lot of coop and run space unfortunately.
The alternative is to run a rotating 7 day collection of hatching eggs. So when eggs get to day 8 they are consumed. If there are any deaths (fox, dogs, wild boar) we can put the hatching eggs for incubation. Problem is in Winter and moult, when we run short of eggs.