Renaming with select() creates duplicate variables with a grouped dataframe

[woodtho]

Renaming a variable, in a select statement, with the same name as the grouping variable results in a dataframe with 2 variables with the same name. There is a warning that the grouping variable was added but no error about duplicated variable names until the variable is referenced.

Not sure if this is the expected behavior, but it seemed weird to me. Especially since mutating a new variable with the same name as the existing grouping variable successfully replaces the original grouping variable.

library(tidyverse)
#> Warning: package 'tibble' was built under R version 4.0.4

(df <- tribble(
  ~prov,            ~value, ~prov_fr,
  "Ontario",         10,    "Ontario",
  "Quebec",          20,    "Québec",
  "Rest of Canada",  30,    "Reste du Canada"
) %>%
    group_by(prov) %>% 
    select(prov = prov_fr, value))
#> Adding missing grouping variables: `prov`
#> # A tibble: 3 x 3
#> # Groups:   prov [3]
#>   prov           prov            value
#>   <chr>          <chr>           <dbl>
#> 1 Ontario        Ontario            10
#> 2 Quebec         Québec             20
#> 3 Rest of Canada Reste du Canada    30

df %>% select(prov)
#> Error: Names must be unique.
#> x These names are duplicated:
#>   * "prov" at locations 1 and 2.


tribble(
  ~prov,            ~value, ~prov_fr,
  "Ontario",         10,    "Ontario",
  "Quebec",          20,    "Québec",
  "Rest of Canada",  30,    "Reste du Canada"
) %>%
  group_by(prov) %>% 
  mutate(prov = "a")
#> # A tibble: 3 x 3
#> # Groups:   prov [1]
#>   prov  value prov_fr        
#>   <chr> <dbl> <chr>          
#> 1 a        10 Ontario        
#> 2 a        20 Québec         
#> 3 a        30 Reste du Canada

^{Created on 2021-04-07 by the reprex package (v0.3.0)}