Fair twins? (2-2)
I believe the answer is:
so-so
'fair' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for so-so that I've seen before include "Mediocre" , "Informally, only moderately good or well" , "Only moderately good in repetitive way" , "Of middling quality" , "Tolerable, indifferent" .)