Indeed? I haven't noticed. And I can't find a decent picture of the dress....
Royal Fashion Police on Instagram is where I saw it; I think it's a "public" account so even if you don't have an account you can see it. According to her, there were 3 sets of outfit twinning:
Flora Ogilvy & Beatrice - the black Self Portrait dress Bea wore for the grandchildren's vigil
Zenouska Mowatt and Good Queen Til - Carolina Herrera
Bea & Mme Macron - Louis Vuitton
I will try to figure out how to upload the screenshot I took of the post, but I make no promises!