Excuse me, is it possible for Guangzhou people to immigrate to Hong Kong and have both Guangzhou ID cards and Hong Kong ID cards?

If you had a one-way permit in the past, your account in the mainland should have been cancelled long ago, and your identity card would be invalid at the same time. If you immigrated as an investor in the past, you don't need to close your account. The mainland ID card is still useful.

The difference is: in the former case, you lost your identity in the mainland and took a non-permanent identity card from Hong Kong. The certificate of going abroad is a Hong Kong identity visa, and you used a home visit permit in the mainland. Seven years later, I changed my permanent identity card and applied for a SAR passport abroad.

In the latter case, your household registration and identity card in the Mainland remain unchanged, and you have a non-permanent identity card in Hong Kong. You will use your mainland identity in the Mainland and your Hong Kong identity in Hong Kong. There is no "Home Visit Permit". Go abroad with mainland passport. Seven years later, I changed into a permanent identity card and applied for a SAR passport abroad.