Delete repeated words, keep the first of each. Optionally ignore case.
It splits the text on whitespace and keeps only the first time each word appears. Later repeats are removed while the original order is preserved.
By default no: 'The' and 'the' count as the same word. Untick 'ignore case' to treat differently-cased words as distinct.
Punctuation stays attached to the word, so 'cat' and 'cat,' are seen as different tokens. Strip punctuation first if you want them merged.