Duplicate removal depends on what “the same” means. Check the available comparison options in the Duplicate Line Remover before replacing a production list.
Test with four lines
Use apple, Apple, apple with a trailing space, and a second exact apple. Exact comparison should distinguish capitalization and trailing space. Case-insensitive comparison may merge the first pair; trimming whitespace may merge another. The right policy depends on the data.
Preserve order when the first occurrence matters. Sort only when sorted output is intended. Leading zeroes, case and punctuation can be significant in identifiers, so indiscriminate cleaning may corrupt them.
Verify the output
Keep the original. Compare counts and inspect removed examples. Test blank lines and lines containing spaces, and check Windows versus Unix line endings if the list moves between systems.
For structured data with quoted fields or embedded newlines, use the format’s parser rather than treating each line as a record. Deduplication is safe only when the comparison policy matches the meaning of the records.