import praw

reddit = praw.Reddit(client_id=client_id,
                     client_secret=client_secret,
                     user_agent=user_agent,
                     username=username,
                     password=password)

subreddit = reddit.subreddit("waifusgonewild")

for post in subreddit.stream.submissions(skip_existing=True):
     submission = reddit.submission(id=post.id)
     for duplicate in submission.duplicates():
         if duplicate.subreddit == post.subreddit:
             post.mod.remove()
             break