R语言返回重复的向量以重复向量的索引

1、测试数据sname.csv

1    a
2    b
3    c
4    b
5    d
6    e
7    e
8    f
9    g
10    f

test <- read.csv("sname.csv", header = F)
test
dupid <- test$V2[duplicated(test$V2)]
dupid <- as.data.frame(dupid)
dupid
dupnum <- which(duplicated(test$V2))
dupnum <- as.data.frame(dupnum)
dupnum