Default [Q] S3 internal/built in memory (not sure about the capacity)

anyone know how this happen?

my GS3 is only 16gb, but when i checked, it says 32768mb on built in memory. the first owner also told me that when he installed a 32gb microsd card in this unit, his files exceeded 50gb. not sure if this is a glitch or something, but i really wanna know if i can use the whole 32gb.

without the sd card, my phone is only 16gb (sd card wont work anymore, its a sandisk class 4 32gb)