In this article I explained some of unique relationship between Tuḷu and Tamiḻ's vocabulary.

Let us see some words with ṟṟa sound. The ṟṟa sound in Tamiḻ becomes tta in Tuḷu language.

1. Forehead: Neṟṟi in Tamiḻ and netti in Tuḷu. 

2. Stump (the part of a tree that remains in the ground after the tree is cut down): Kuṟṟi in Tamiḻ and kutti in Tuḷu. 

3. Cow: peṟṟa in Tamiḻ and petta in Tuḷu.

Some Tamil words have ṉṟ sound this becomes nj in Tuḷu. 

1. Calf: Kaṉṟu in Tamiḻ and kanji in Tuḷu. 

2. One: Oṉṟu in Tamiḻ and onji in Tuḷu. 

3. Pig: Paṉṟi in Tamiḻ and panji in Tuḷu. 

(*In the above examples Tuḷu words ends with -i sound & Tamiḻ word ends with -u sound, this is because Tuḷu separately emerged from south proto Dravidian, So Tuḷu have such unique features which can't be seen in other Proto South dravidian Languages.)