I have been observed that if I refresh the post the count of viewed shown below at the end of every post also been increased. I guess the functionality should count only the counts and increase if the users viewed that post first time. There must be having some logic which check IP and increase count.
Personally I dislike it when people tell me what needs to happen, especially when they say that it "must be".
As to the overall functionality - we can't just use IP addresses, as many places (e.g. schools, businesses, libraries, ...) use a single IP address, so restricting on that criteria would simply change the problem from one where a topic might have a too high number to one where a topic might have too low a number. In addition, this implies storing data on the server side on what pages every visitor (signed in or not) has viewed for all time - the potential database table would be huge. There are worse problems to consider if you try to save that information client side.
I'm don't see this as a high priority, especially given the complexity involved in getting accurate counts and the relatively low value in trying to get them accurate. It is not like there is any competition to see which topics are viewed the most.