The term ONE AND ONE can be expressed in three different ways: TWO (3 letters), PAIR (4 letters), and DUO (3 letters). TWO is a number that is one more than one, and it is often used to refer to TWO people or things. PAIR is a set of TWO similar or identical items, usually referring to TWO people or things. DUO is a PAIR of people or things, typically working together in some way. All three terms refer to the same concept of TWO people or things being together.