Merenre II is only attested to in the king lists. The Turin canon assigns him a reign of less than one year. It is assumed that he is a son of Pepi II, but he is otherwise unattested.  

Merenre II is sometimes called Nentimsaf II, which is the same name as Merenre I -- since the egyptians didn't use the numbering system for pharaohs, that's our invention, we would not be able to tell which person they are referencing. For that reason, some believe that the name Merenre was mistakenly attributed to Nemtimsaf II.

Based on historical documentation for his possible successor, his sister/wife Nitocris, Merenre II was murdered while on the throne.