Feedback after a few months on twitter and foursquare

after a few months on twitter and foursquare (4sq) I have two wishes to make:
Twitter: what about a way to avoid double twits ? I frequently receive numerous times the same twits either from the same twitty bird either via RT. There should be a way to compare a new tweet with the previous ones you received and so avoid all those double twits.

 On Foursquare I hate those doubles venues nearly spelled the same way but only "nearly". I found numerous of those "doubles" that could be avoided. Comparing the "close" spellings or words with the location of the checking. I was wondering why those doubles are not stopped when you create a new venue ?