Does it fair for me to go back and not the other employee

Me and other employee has shoulder surgery a week apart. But the case manager from work told my doctor that they have a light duty work for me, the other employee has shoulder surgery a week before me and still off, even that I told my doctor that I have pain every day. When I ask the case manager about why I have to work and the other employee don't , she told me that she has some personal problems to resolve and it has been a month already. Does these scenario is normal. The other employee has been working for the company for 23 years and I have been just 18 month at the job. Other thing is I am one of the hardest worker in the warehouse too, I think they brought me back because there were short handed on second shift. I am going to get a second opinion from another doctor, I feel that is unfair for me to go to work every day with pain.