I've always done 'sort | uniq'. Never bothered to check for the the unique flag to sort. Although 'uniq -c' is quite nice to have.

       -c, --count
              prefix lines by the number of occurrences

▲ adolph 2 hours ago | parent [-]

Yeah, to see the packages with multiple versions:

  grep 'name = ' ms-litebox-Cargo.lock | sort | uniq -c | grep -v '1 name' | sort -n

Package windows-sys has the highest number of versions included, 3: 0.59.0, 0.60.2, and 0.61.2.

Edit: Also, beware of the unsorted uniq count:

  cat <<EOF | uniq -c
  > a
  > a
  > b
  > a
  > a
  > EOF
   2 a
   1 b
   2 a

	▲	dundarious 2 hours ago \| parent [-]
		grep -v '1 name' excludes 11, 21, etc., but I take your point.