bug#32450: uniq -f: unexpected behaviour

[helo]

Package: coreutils
Version: 8.26-3

uniq -f shows other behaviour with characters than with numbers

# works as expected in #  
echo "a a a
a b c
a a d
b d d" | uniq -c -f2

      1 a a a
      1 a b c
      2 a a d

# works somehow different #
echo "1 1 1
1 2 3
1 1 4
2 4 4" | uniq -c -f2

      1 1 1 1
      1 1 2 3
      1 1 1 4
      1 2 4 4