May be these are the answer to "요즘 어떻게 지내세요?"(How are you these days?)
and both mean the same thing.
A : How are you these days?
B : Nothing Special. / Not bad. / So so. / ("I'm fine." means almost the same I think.)
늘 똑같지요, 뭐. -- Nothing special.
그럭저럭요. -- Not so bad, not so good.