Facebook Detects Duplicate Status Updates

Facebook is reading "What's on your mind?" . Yes this is the thing that Facebook asks you when you are about to post an update over it and they really mean it as they read it very carefully. You might have came to this thought when Facebook shows grouped post having common  topic about which you are talking about like A friend's Birthday or a festival etc.Today while using Facebook I came across a very new familiar situation. I was updating my status and then by mistake I Re-pasted the same status again , I got a popup from Facebook saying:

Duplicate Status Update
This Status is indentical to the previous one.

It was quite useful as it saved me to make the same update again, this is called the smartness of a social network and I think its possible in only Facebook.

Have ever been encountered by this situation?
What would happen if Facebook reads/checks all your previous messages for duplicability?
And what about checking the statuses of the all Facebook users for duplicability?
Will it then restrict the spamming bots and the manual viral copy paste statuses/posts on Facebook? Do comment.