When are you authorized to wear two of the same ribbon?

When you have received one for service and one for valor (Bronze Star). When you have receive 10 or 21 of the same .

another AAM

Thank you for that answer. I have never seen myself.

Well, I went thru Air Mobile School at Ft. Campbell in 1974 and got that badge, I wore it for 10 years.
Then I went back to Ft. Campbell in 1984 and went to Air Assault School and got another!
Both are listed seperately on my DD-214!

I thought they just put an oak leaf cluster on one ribbon.

I was authorized to wear two of the same ribbon. It’s because of a loophole (weirdness?) in AR 670-1 that doesn’t cover the tenth award of any oak-leaf based medal set. And yeah, I had ten AAMs, too.

How do you wear a bronze star for valor and a bronze star for meritorious service

It’s usually a cluster added to the one ribbon

I have 4 AAM'S and 1 MSM. Wasn't awarded an ARCOM until I retired.

I too only seen this once on my drill sergeants dress uniform