Its the same scoby. It grows and grows. Whenever it gets big, like 3in thick, I pull it out, pour out the booch,
clean the jar, and rip about 1/2in of the scoby to put back, and pour the booch back in. I feed the rest of the scoby to the chickens. :) I do this probably every 4-6 months-ish, I think.