It seems common in advertising, but is it used in speech?
I don't think it's commonly used in everyday conversations. To say 'we all', we usually use 我々みんな, 僕たち全員, etc., depending on the formality.
If you ask if it is commonly used in ordinary speech, the answer is no, but I don't think it sounds particularly weird to use that phrase in ordinary speech. I just can't think of a situation where I would say "I" twice like that in an ordinary context.