This is a comparison that is thought to mean the same thing, or when two options would produce the same result.
那是半斤八兩----彼此相當，不分高下。
「台斤」一斤 16 兩，半斤等於 8 兩。當兩者相較，不相上下、無分軒輊，或勢均力敵、平分秋色時，便可如此說----因為一打 12 個，半打等於 6 個。