I use the RSS feature to monitor when someone mentions me on twitter. I subscribe to https://nitter.net/search/rss?f=tweets&q=%40my_twitter_handle for my different twitter handles and when there is a mention, the tweet appears under my Unified Folders as a new message that I can read, unread, tag etc like an email message. This is very useful because I don't have to check twitter all the time, and nitter standing in the middle also enhances privacy. This works well with two of my three handles, but the third one generates duplicates all the time. I have been monitoring this for weeks and so far I got up to five copies of certain tweets. There is nothing unusual about this twitter account either. This looks like a bug as the other two handles work fine. Also, another RSS reader I use for comparison doesn't generate a single duplicate.