For privacy protection and account security, one account can only be allowed to log in on one phone at the same time. If the same account is logged in on the second device, it will be forced to log out on the first device.
However, if you want to access your camera on two or multiple devices, you can achieve it by sharing the camera.
Only the main account with cameras set up has the right to share his/her camera with other devices or people.
Please make sure the shared user has been registered and logged in to the App first.
Please make sure the shared user is in the same login environment/country as your main account (owner).