While Nina has been told about the babies' gender, there's a thing about the twins that the couple has still keep a secret from her.
"It will be one of each!"
"I think he'll be great, and I think she'll be a great mom!" she told Us Weekly.
The news was announced by Julie Chen, a host of United States chat show The Talk, who is said to be very connected in Hollywood.
George and Amal Clooney may want to share pregnancy notes with Beyonce and Jay Z.
Amal is due in June.
George, 55, and Amal, 39, were married in Italy in September 2014.
Damon, 46, praised human rights lawyer Amal Clooney, 39, calling her "a remarkable woman" and saying George Clooney had "hit the jackpot". And I was like, "How far along is she?' And he goes, 'Eight weeks".
'Congratulations are in order for George and Amal Clooney'. "She said she's giving the kids all the great books she read as a child", the source said, "and told the check out lady that she never thought this day would come!"
'It was just a personal moment, ' she continued.
The news was first made public on Thursday (09.02.17) when the couple's close friend Julie Chen made an announcement during her talk show "The Talk".
Speculation Amal was pregnant mounted when she was pictured in baggy clothes at events including a screening for Netflix documentary The White Helmets.
Now that the news has been confirmed, the three-time Golden Globe awardee and his British wife are set to welcome their first-born twins in June based on reports from The Sun. Just on every level.
Damon said: "They're going to be awesome parents".