There is zero benefit to having two small social democratic parties fighting for the same vote - why don't they merge (after all the SDs come from the Labour gene pool)? The resulting economies of political scale could see them become a proper force in Irish politics again and one that could be seen as potentially crucial coalition partners when it comes to forming the next government.
If they want a name, I'm sure their northern friends wouldn't raise too much fuss if they call themselves the SDLP. 😉