Why can Shenzhen and Guangzhou pay double social security?

The state recognizes only one. Because paying social security in two places at the same time can't enjoy two retirement benefits, even if you pay three social security benefits, you can only enjoy one social security benefit, including pension insurance and medical insurance, and you can only enjoy the benefits of one region. Don't think it's a good deal to pay two social security payments, but you actually lost a lot of money.