I happened to hear Nammakkul Yaen Anbae Anbdae yaekkam song form the movie Kathal Devathai. They reused the tune Madura Marikozhundhu Vaasam from Enga Ooru Paatthukaaran movie. Or it the other way? I could not find the year of KD in raaja.com
I also recollect that the original version of "Enna samayalo" from Unnal Mudiym Thambi is in Manipoor Maamiyaar. Ofcourse lyrics is slightly tuned.
On the BG score, I remember that the second interlude of Poongaattru Pudhidhaanadhu is reused in En Vaazhvilae Anbae vaa in Thambikku Endha Ooru. Ofcourse, both are such a beautiful songs. I also heard about the health condition of IR during TEO.
Just thought of sharing this. Any other instances like this?