How to Remove Duplicate Lines From Text

What is a duplicate line?

A duplicate line is a line of text that appears more than once. Removing duplicates usually keeps the first occurrence and removes later repeats.

This is useful for copied lists, email exports, IDs, keywords, URLs and other line-based data.

Want to try the idea yourself? Use the Remove Duplicate Lines.

Exact duplicates vs near-duplicates

Two lines can look similar without being identical. Extra spaces, different capitalisation or punctuation may cause a strict duplicate checker to treat them as different.

For example, “London” and “london” may or may not count as duplicates depending on whether matching is case-sensitive.

If you want to explore this topic further, see How to Count Words and Characters in Text.

Be careful with meaningful repeats

Repeated lines are not always mistakes. A list of transactions or survey answers may legitimately contain the same value more than once.

Only deduplicate data when each line is intended to represent a unique item.

Preserving order

A useful duplicate remover keeps the first occurrence in its original position rather than sorting the entire list automatically. This allows you to clean the data without changing its sequence.

If you also need alphabetical or numerical sorting, do that as a separate step so the changes are easy to understand.

Clean a list quickly

Paste the text into Remove Duplicate Lines to create a cleaned version without manually hunting through a long list.

Compare the number of lines before and after if you need to know how many repeated entries were removed.