Actually it's really wise to have 3.
The reason you need more than one file is because your resume is likely to be scrutinized by a computer before a human ever sees it. And that computer uses ATS parsing software to 'read' your resume. ATS parsing software prefers plain text files because it is only looking for text. Graphics, formatting, and other things that humans like to see can confuse it. Since plain text files are stripped of formatting and graphics, a plain text (*.txt) file is the preferred file for ATS parsing. Therefore always create a plain text (*.txt) file for applying online.
Fortunately for us humans, ATS parsing software can also read most *.doc files produced by Word as long as they don't include graphics and document generate attributes that confuse parsing. So a Word doc file is the second file we should have. Although the software can read doc files, parsing software has less difficulty reading *.txt files.
The third file you probably want to have is the fancy one that is attractive to the eye. The things that make it shine will almost always cause ATS issues and will result in either outright rejection or at least non-response. I call these files "For Handout Only". You can use them to physically hand to people in interviews or when networking, but the risk is all yours if you try to apply for a job with them.
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