How long is it since she had the first litter?
Pregnancy and rearing pups does take a lot out of the females so it is ideal to space litters out to allow mum to rest. Obviously what's done is done in this situation, but I would recommend taking strict care to prevent her becoming pregnant again in future as two litters is more than enough
If the male and female hamsters are in the same cage, please separate them as soon as possible. This will prevent the female becoming pregnant again when she gives birth and also Syrian hamsters should live alone. Make sure they never have any 'play dates' and that cages are secure to prevent her becoming pregnant again.
Who is caring for the hamsters when you are away? They will need good instructions about the care of a pregnant hamster and new litter.