How to prevent one person from logging in from different accounts at the same time?

Question

User identification

We need to create a system for secure voting. All voting participants are known in advance, it is possible to install the application on the user's phone. What methods can be used to strictly assign one account to one user? (we consider all voters to be dishonest, they can exchange passwords or even hardware) [the main task is to prevent one person from voting instead of another]

Answer 1

With such a setting - no way. The malware will simply take a mobile phone from a friend and do its job.

Answer 2

Use the credit card number and CVV of a specific user as an authorization key so that they do not rummage them among themselves. With this formulation of the question, no more.
Well, a soldier with a rifle.