If memory serves, Tupac has 'released' nine albums since his death.
With modern technology, it is increasingly easy to take a simple vocal line or a fragment of a song and create an entire track around it.
Because in common with most recording artists, Tupac worked out material in the studio, there are masses of 'off-cuts' from recordings and rehearsals that he would judge as sub-standard, but which are enhanced and released to meet the increasing demand for his music since his death.