Desert Eagle

When you see several dates in a copyright statement, it simply means that certain things were created in one year and modified later. It could also mean that new things were created and added in a later year. It most definitely does not refer to the date that a copyright will expire. Expiration of a copyright actually takes place much later, and this period of validity begins from the date that you see in the copyright statement. The Berne Convention establishes a general and minimum period that lasts the life of the author and fifty years after his (or her) death. Cinematographic works and photographic works have a minimum period of protection of 50 and 25 years upon the date of creation, respectively. This applies to any country that has signed the Berne Convention, and these are just the minimum periods of protection. A member country is entitled to establish greater periods of protection, but never less than what has been established by the Berne Convention.
So, what does all this mean? This means that if a copyright statement reads, “?Copyright 1998, 1999 John Smith” and John Smith is from a country that has signed the Berne Convention, he created his works in 1998 and 1999, and his copyright is not going to expire until at least fifty years after he dies (this period may be greater – remember that member countries may establish longer periods of protection). Until that time his works are not in public domain.  I have actually seen copyright statements with future dates, such as “?Copyright 2003, 2004 John Smith”, most likely because the copyright holder thought that they could establish an expiration date for the copyright. This is incorrect unless John Smith traveled to the future and created the work in question. These types of copyright statements also mislead others to believe that dates in a copyright statement refer to the date a copyright expire, when the date should really refer to the date of creation.
From:Microsoft website