fwrite doubles quotes (") in strings to ("") #6723

When character variables contain quotes (") in strings, these quotes are doubled in the written csv. I don't know if quotes (") in strings should be supported by data.table.

This are the input and Output CSV after reading and writing the csv with fread and fwrite. All " are doubled except the text classifier ".
Input-CSV:
um_var1,string_var, num_var2
1,"test "nr" string1",4
3,"teststring with double quotes ""Dictator perpetuo"" that are wrongly written when using fread and fwrite",5

using fread and fwrite to read and write the CSV leads to following CSV-file:
Output-CSV:
num_var1,string_var,num_var2
1,"test ""nr"" string1",4
3,"teststring with double quotes """"Dictator perpetuo"""" that are wrongly written when using fread and fwrite",5

The problem remains when using the quote parameter of fread().
This is the code that read and wrote the CSV-files:

`
quote_test <- data.table::fread("string_with_doublequote.csv")

data.table::fwrite(quote_test, "quote_test_out2.csv")
`
quote_test_out2.csv
string_with_doublequote.csv