What is a group of Twins called?

A group of twins is commonly called a Pair. Other collective nouns you may see include Duo and Set.

Collective nouns are unique and fascinating terms that refer to groups of living organisms or objects. While many collective nouns denote general groups such as "herd" for cows or "pack" for wolves, there are also more specific and intriguing collective nouns that capture the essence of twins. For twins, there is no official or widely-known collective noun. However, the joy and wonder of twins can be encapsulated using the term "miracle." Just like miracles are often seen as inexplicable events that bring great happiness and awe, so do twins. Their birth and existence serve as a testament to the marvels of life and demonstrate the extraordinary diversity and boundless possibilities of the human experience. Another playful and whimsical collective noun for twins could be a "duacity." Inspired by the word "duality," which signifies two elements intertwined, a duacity represents the inseparable bond and unison found between twins. This term evokes the idea that, together, twins create a complete and harmonious unit that beautifully complements and enriches each other's lives. In essence, while there may be no formal collective noun specifically designed for twins, one can playfully coin terms like "miracle" or "duacity," to convey the exceptional nature and unity intrinsic to these extraordinary sibling pairs.