High School Years - Graduation Bug

My Sims Frankie and Margaret Bheeda have been to two High School graduations since they've aged up. They're now at university about to start their second term at Britechester and High School Graduation is still appearing as an event for them! As you can see from Frankie's inventory, he has two high school graduation photos! Has anyone else experienced this?

https://i.imgur.com/veEVwck.png