why a long numeric value changed after converting the variable from character to numeric?

Question

I concatenated some varibales to create an ID, I created two types of variables concatenated (both with same values), one in a string format and the other in a numeric format. But the result differs in the last 2 digits, it supossed to be the same, I used the same values

id_viv <- SD %>%          
  mutate(id_viv = 
     as.numeric(paste0(cd_a, ent, con, v_sel,
                                    n_hog, h_mud, n_ren, n_pro_viv)),
     id_viv_char = (paste0(cd_a, ent, con, v_sel,
                         n_hog, h_mud, n_ren, n_pro_viv)))

At first, I thought those values were exactly the same and they were just different in a visual perspective. So I tried to compared both with the duplicated function but they were actually different...

first result

table(duplicated(id_viv$id_viv))

output:

FALSE   TRUE 
403296    356 

second result

table(duplicated(id_viv$id_viv_char))

output:

 FALSE   TRUE 
 403644      8 

Someone knows why this happen?

P.S: This also happens in STATA