If you have the stock and the nest boxes, it's not a bad idea to have two does bred/kindle the same day. It opens the possibility of fostering kits.
Depends a lot on how many does you have. I've got several does and usually breed 3 to 5 does at a time. If you only have two or three, it may not make as much sense.
That's on the "front end"...
Another question to answer is what will you do with all those kits once the kindling and fostering are over? You may be set up to handle 8 to 10 grow-outs at a time but not 20 or 30.
(Don't you just hate answers that start out "It depends..."?) Good luck to you!