In IMDB there are also 2 profiles.
Are you sure they are two different people ?

Kostas Tsakonas (I) (1943–2015) or Kostas Tsakonas
https://www.themoviedb.org/person/1119990-kostas-tsakonas?language=en-US
https://www.imdb.com/name/nm0874655/

Kostas Tsakonas (II) or Konstantinos Tsakonas
https://www.themoviedb.org/person/2573449-kostas-tsakonas?language=en-US
https://www.imdb.com/name/nm1317869/

Yes, you're right. Indeed there are 2 persons. The problem occurred because in some comedy movies Konstantinos Tsakonas inserted instead of Kostas Tsakonas as the actor, because in Greek language the name "Kostas" is the short nickname of "Konstantinos" and is very easy to misread/misunderstand the correct one. Kostas Tsakonas is a well known comedian in Greece, while Konstantinos Tsakonas is known, mainly for his dubbing work and secondary for his drama roles.

I'll fix the errors in the movies and I'll upload a photo of Kostantinos Tsakonas, so the future contributors will not be confused.

Regards

Thank you very much