Two sounds of 50 db each will NOT constitute a 100 db sound. This is because, the relation that relates levels of sounds is a logarithmic relation and not a direct relation of addition. Each 10 dB increase in sound makes the sound 10 times louder.
This means that, for 50 db, the resultant sound level will be twice as loud is an increase of 10Log (2) = 3.01dB
The final sound level = 50 + 3.01 = 53.01 db