Shareholders of a one-person company have to pay personal income tax for dividends, so don't two or more people have to pay it?

According to Article 8 of the Individual Income Tax Law,

Personal income tax, the income is the taxpayer, and the unit or individual who pays the income is the withholding agent.

According to Article 35 of the Regulations for the Implementation of the Individual Income Tax Law,

When withholding agents pay tax payable to individuals, they shall withhold and remit the tax in accordance with the provisions of the tax law, pay it to the treasury on time, and keep special records for future reference.

Therefore, your company should withhold and remit personal income tax when paying dividends. Shall not be paid together with the next year. Otherwise, the competent tax authorities will impose a late fee on overdue taxes and impose penalties according to the Law on Tax Collection and Administration.