Each person’s medical needs can differ. Do you both see the same physicians? Do you both have the same prescription drug needs? Do you both have the same medical history and/or current medical needs? Do you both live in the same region and have access to the same carriers/insurance plans?
With Medicare Part A (hospital benefits) and Part B (outpatient services) in place, you can then consider which of the Medicare Advantage/HMO plans and/or Medicare supplements and stand-alone drug plans that are available in your area will best fit your medical and prescription drug needs.
If you are overwhelmed by the options available to you, I recommend that before signing up for the same coverage your brother has selected (which may or may not be appropriate coverage for you), that you first consult an agent in your area to sort thru which coverage(s) will fit your needs before making your insurance election decision.