I've heard of having to go through multiple interviews to get the job, but someone was telling me some jobs require multiple (different) resumes. Is this true? If so, when does it normally happen? I'd like to know so I can better prepare myself. (If relevant the guy claiming this is a doctor so maybe it's common in the medical industry).
Generally, this is not done, as already covered by the other answers.
The only exception I can think of is when the resume submitted has become out of date. In one case from my own experience, I submitted a resume to a company, but was initially turned down. Six months later they contacted me and said they had an opening that matched the qualifications they saw on the resume I had submitted. I submitted an updated resume because I had some new experience that made me even better for the position.
From a comment clarification:
..Needing to have one resume to get through "the first round" then another for the second round (with the same company) etc
Honestly, I have never, ever heard of this as a requirement. Just think this through. How is it supposed to work? Your work history and experience hasn't changed, and the position description and requirements haven't changed. What are you supposed to change in your resume?
This sounds like someone has misinterpreted or misunderstood the common wisdom of tailoring your resume to each role that you apply for. Just refine your resume such that shows how your experience and skills best fit a particular role, and then it will stand as it is throughout the recruitment process. If they want more clarification, they'll ask you in an interview.
The only time I could see this being done would be if the first round was a recruiter screening, and then they ask you to refine your resume before passing it to the company (your applications should be different on a per-application basis anyway).
Worth pointing out that I would avoid changing my given details mid-application, as that may indicate that you're trying to hide something, or are being less-than-truthful about some aspects.
but someone was telling me some jobs require multiple (different) resumes.
Someone is having you on. An interviewer would probably start looking at you sideways if you changed your resume partway through the process.