It’s a form of contrastive reduplication. Used to emphasize the realness of the experience, versus like second hand experience like interviewing those who have the actual experience.

Also consider a phrase like “work work” versus “school work”. For someone who both works a paid job and goes to school, clarifying that they need to do “work work” makes sense.

You can experience things second hand. I wouldn’t object to someone saying ‘my experience with chemo’ when talking about their spouse’s disease. They can tell you not just the symptoms but what their insurance company did etc.

Still while watching a loved one deal with cancer is an intense experience and gives you way more insight than you had before you didn’t have the lived experience of having cancer, thus the distinction.