What is the context for using this
Looks like it shows approval or agreement, as in "you can say that again".
If it didn't start with "moran taing" then it might mean "can you repeat that".
I thought it was more along the lines of politely asking a person to repeat themselves.
Maybe someone finally gave the right answer in class?
Somebody gave you a compliment and you want them to repeat it. :D
"Many thanks, say that again." she said, pad and pen in hand.
Could 'thanks very much' be accepted too?