Companies differ in the way they price their plans. Companies also differ in customer service. Contact different companies and compare before you buy. If your income is low, you may qualify for a government program that will help pay your Medicare costs. One plan is enough Medigap plans are designed so that you do not need other similar coverage.
Duplicate coverage can be expensive and is generally unnecessary.
It is illegal for an insurance company to sell you a second Medigap plan. It is also illegal to sell you a Medigap plan if you are in a Medicare managed care plan. You should also ask if your state helps pay your Medicare costs for persons with limited income. If you have a health problem, and the company limits or excludes coverage for pre-existing health conditions, the insurance company might not cover your costs for any care related to that health problem. On the other hand, do not keep an inadequate plan simply because you have had it for a long time.