---
title: "duplicated rows"
output: pdf_document
---

```{r}
library(dplyr)
library(kableExtra)

tbl1 <- bind_rows(mtcars, mtcars, mtcars, mtcars)

kable(tbl1, longtable = T, row.names = 1:128) %>%
  pack_rows(index = c("g1" = 3, "g2" = 6, "g3" = 5, "g4" = 5, "g1" = 3, "g2" = 6, "g3" = 5, "g4" = 5,
                      "g1" = 3, "g2" = 6, "g3" = 5, "g4" = 5))
```