So, I dont think they are the same person.
Pallavi D Iyer was a remarkable person, natural-born musician, and
composer, in his own right. He was born in 1782 and died at the age of
34. In this brief span, he produced about 50 compositions. The article
laments that very few of these compositions are heard today. There is a
charming story about how he curbed the arrogance of some vina players in
Thanjavur by writing a krithi containing notes and sounds which they could
not produce.
He was born in, where else, Thiruvaiyur. In addition to his musical
ability, he was a very gifted painter and calligrapher.
I obtained this info from a little volume called "Great Composers" edited
by Gowrie Kuppuswamy and Hariharan. It consists of about 30 articles on
various composers taken from "The Hindu". For example, there is a piece
about Swati Thirunal written by Semmangudi. The particular article about
Pallavi Doraiswamy Iyer was written by M.Visalakshi.
Sriram