I find I crack through 24-pot trays far more efficiently when I've Jon Bon Jovi singing to me as the rain falls gently on the glass house.
I filled 3" pots with B&Q's finest then push two beans per pot about half an inch into the compost. Conventional horticultural advice always rattles on about double sowing then discarding the weaker of the two. I think that's a bit miserable, actually; if the seeds make the effort to grow the least we can do is plant the two together. And let's face it, two bean seeds planted a few inches from your 8' bean stick isn't going to have any detrimental effect.
Here's the laundry list;
Buerre de Rocquencourt - that's the yellow pod
Amethyst - that's the purple one
Cordon Bleu - the green one. Oh, OK.