pthread_create is called multiple times while the previous thread with same routine is running

Question

Is there any memory leaked or any other problem in second pthread_create call (e.g: memory allocated for pthread) if I accidentally call to pthread_create twice while the previous thread with same routine is running?

static void* thread_routine(void *data)
{
   while (1) {sleep(1)}
   return NULL;
}

int main()
{
    static pthread_t thread_id;
    pthread_create(&thread_id, NULL, thread_routine, NULL);
    pthread_create(&thread_id, NULL, thread_routine, NULL);

    while (1) {//> never return <//}
    return 1;
}

Thanks for your helps/answers.