Google’s John Mueller answered a question in the Google Hangout at the 19 minute mark about is it better to go with short or long URLs. We know Google said don’t go over 2,000 characters in your URL and we know Google may try to shorten your URLs over time.
In short (no pun intended), John Mueller said that when Google notices two URLs on a site with the same content, it will tend to go with the shorter URL.
He said:
Here is the video embed at the start time:
