Error in Launching 2 chrome browsers using MultiThreading and perform same functionality simultaneouly

I am trying to launch two chrome browsers Simultaneously using Selenium ad cucumber, and perform same operations using multiThreading, but on one browser, operations get complete, whereas on another browser, browser is launched, but nothing else is performed, not even window Maximize, or navigation to endpoint URL

below is my code Snippet:

public class TraderViewStepDef extends Thread implements Runnable {

WebDriver driver = utils.driver;
UIGeneral uIG = new UIGeneral();
Common_Step cs =new Common_Step();

@When("Open event simultaneously to check message {string} {string}")
public void openEvent(String user1, String user2) throws InterruptedException {

    Thread t1 = new Thread(new TraderViewStepDef());
    Thread t2 = new Thread(new TraderViewStepDef());
    t1.setName(user1);
    t2.setName(user2);
    t1.start();
    Thread.sleep(6000);
    t2.start();
    t1.join();
    t2.join();
}
@Override
public void run() {
    try {
        System.out.println(Thread.currentThread().getName());
        uIG.userLoginAsIn(Thread.currentThread().getName());
        
    }
    catch(Exception e)
    {
        e.printStackTrace();
    }

}

public void userLoginAsIn(String userName)
{
    getDriver();
    driver.manage().window().maximize();
    driver.get(endpoint);
}

}