You can create an randomized array but it will not guarantee a repetition. For example you have 4(numbered as 0,1,2,3) events. You put them in an array and shuffled it. And on every 4 events you will shuffle again
Group 1 Group 2 Group 3
(0,3,1,2) (3,2,0,1) (1,3,0,2)
Between passing group 2 to group 3 same event will re occur.
Still, such an approach will reduce repetitions.
https://drive.google.com/file/d/102s4OHmnjeMfRpmxt-jDYrLon65z-HkU/view?usp=sharing