no
the novel is lakshmila- the eternal love story
by shubi agarwal
it's written in that novel that it's based on valmiki ramayan and other versions
in that novel
it's mentioned that the cousins were of same age
shrutakirti was a year younger than them
in dandi ramayan
sita and urmila were both born through yagya not from womb
mandavi and shrutakirti
(their names were bit different there)
they were twins born to kushadhvaj and his wife
they were born through womb

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