That would depend on the "charging instrument". A lot of traffic tickets aren't really all that formal. It matters what the Information says and what they are alleging. Speeding is a charge that really just requires the State to prove that you were driving over the speed limit beyond a reasonable doubt. How the officer writes it up on the ticket might be a factor in disproving their case at trial, but I don't think it will be an automatic trip to a dismissal.
Any speed over the speed limit is a valid speeding charge. Officers usually have discretion on whether to write you a ticket or not. Not common for an officer to write someone a ticket for only 2 miles over the speed limit, but they can.