there was a conversation between Lord Bramha and Saint Valmiki about
beautifulness of Lord Vishnu in Sayana pose. This conversation led
to fight between the two. Lord Vishnu appeared before them and said
"In Sayana pose I am beautiful here". So Lord Vishnu was
called as "Vadhivazhagiya Nambi".
Once when Manduga Maharishi was in penance under water. Saint Dhuruvaasar
waited for him on the water shore long time. Since Saint Mandugar
has not turned up, Saint Dhuruvaasar cursed him to become frog.
So Saint Mandugar came to this place and did penance on Lord Vishnu.
Lord Vishnu appeared before him and whipped off the curse given
Saint Dhurvaasar and Saint Mandugar regained his form. So this place
was previously called as "Mandugaapuri". The pond here
is also called as "Manduga Theertham".
Once when Thirumezhisai Alwar came here, he was teased to a great
extent by the people. He taught of teaching them a lesson and sung
a song on Lord Vishnu to appear on him and make the people know
that he is Lord Vishnu's ardent devotee, and Lord Vishnu came out
of Thirumezhisai Alwar and appeared here as "Vadhivazhagiya
Nambi" to make Thirumezhisai Alwar to teach them a lesson.