i am not sure sure. the bronzes were part of a hoard that were buried intentionally. such were done to escape the dark period around 1314. so just because a bronze is found along with the plate doesnt mean both are same period. there are inscriptions for eg which talk of sepptuh thirumeni of rishbantakar ( the famous tanjore museum exhibit) that say it was cast in 1011 and his consort umai in 1012. unless we can find a similar inscriptional reference to the casting of such a manikkavasagar bronze - it will not be clear proof