I did the exact thing, and got the same response. My NOA2 date also changed.
My approval notice says “The above petition has been approved. We have sent the original visa petition to the Department of State National Visa Center.”
I don’t have a number next to my name, but there is one next to my fiance’s name, that is the Alien Registration Number.
I think NOA2 date and Approval Date are different so you can keep referring to 7/28 as your Approval Date, 8/24 is just the date of this notice.