Police said the two had objected to Palanisamy (70), building a compound wall for his proposed house on his land, which they alleged, encroached on their land.
The duo noticed Palanisamy at the construction site yesterday, stabbed him with a knife and fled, police said.
Passersby noticed the old man lying in a pool of blood and rushed him to the Govermment Hospital here, but he died on the way, police said.