Hi,
Is this what you're looking for:
library("dplyr")
myData = data.frame(villageid = sample(1:10, 50, replace = T), attendance = sample(1:5, 50, replace = T))
duplicates = myData %>% group_by(villageid, attendance) %>% summarise(n() > 1)
myData = left_join(myData, duplicates, by = c("villageid", "attendance")) %>% arrange(villageid, attendance)
Grtz
PJ