Split double-columns into separate columns and merge same-named columns

This has been a tricky problem for which I am really excited to hear solutions. I have what I call "double-columns", i.e. columns of which the content can be split into two separate columns.

This is my input:

structure(list(`A1-A2` = c(2, 1, 1), `A1-A3` = c(2, 1, 2)), row.names = c(NA, 
-3L), class = c("tbl_df", "tbl", "data.frame"))

# A tibble: 3 x 2
  `A1-A2` `A1-A3`
    <dbl>   <dbl>
1       2       2
2       1       1
3       1       2

For one column, I can demonstrate what I want to do, but not for several:

data %>% 
  separate(`A1-A2`, into = c("A1", "A2"), sep = ":") %>% 
  mutate_at(.vars = c(1:2), as.numeric) %>% 
  mutate(A2 = A1 -1) %>% 
  mutate(A1 = ifelse(A1 == 2, 0, A1))

# A tibble: 3 x 3
     A1    A2 `A1-A3`
  <dbl> <dbl>   <dbl>
1     0     1       2
2     1     0       1
3     1     0       2

• This splits the A1-A2 column into two separate columns A1 and A2.
• If its value was 1, sets 1 into the left column (A1)
• If its value was 2, sets 1 into the right column (A2) This only works, as you can see in the code above, for splitting 1 double-column.

Two challenges:

1. How formulate my code in a generic format for any number of double-columns?

2. How can you avoid problems because several split columns have the same name (e.g. when the double-columns A1-A2, A1-A3, A2-A3 are split, they will have A1, A2, A3 occurring twice)??

Approaches in tidyverse (purrr::map) are preferred, but I am open to other solutions.

Tricky, isn't it?