My rabbit had babys?

How old do you think the current litter are? Have they got their eyes open? If she has been with the buck the whole time then I'll ume she got pregnant again the day after giving birth, so you will need to take the current litter out as soon as she starts nesting and take them to the vet for advice. They will nibbling solids by then, but the mother should feed until 6 weeks at least so they will need some formula once a day.