$query = mysqli_query($con, "SELECT * FROM users WHERE Username = '".$testname. "' OR Email = '".$testemail. "'");
$registered = time();
if(mysqli_num_rows($query) > 0){
    echo "Username or email is already in use.<br>";
}else{
    $sql = "INSERT INTO users (Username, Password, Email, Firstname, Lastname, Lastlogin, Registered) VALUES ('$testname', '$testpass', '$testemail', '$testfirstname' , '$testlastname', '$lastlogin', '$registered')";
    if ($conn->query($sql) === TRUE) {
        if($sql->errno === 1062) {
            echo "Username or email is already in use.<br>";
        }else{
            echo "New account created successfully<br>";
        }

    }else{

    }
}