unique visitor tracking - not working (no replies)

Have an issue where I have loaded up a month work of apache log data, but the unique visitor identification doesn't seem to be working correctly.

For example, we have a monitoring server that runs through a script against the site every 5mins to check that it's up and page responses are working. Therefore, this IP shows up every 5mins in the logs as a new visit. Unfortunately the IP is being tracked as a new visitor for some of the visits. I determined this by drilling down to a day and creating a segment with just that IP. The reporting shows the IP as 7 unique visitors - which i guess is better than 1 for every 5mins. I'm just puzzled as to why it would do this since it's the same IP.

My unique visitors config seems to be set correctly to me based on the documentation.
[General]
enable_processing_unique_visitors_day = 1
enable_processing_unique_visitors_week = 1
enable_processing_unique_visitors_month = 1
enable_processing_unique_visitors_year = 0
enable_processing_unique_visitors_range = 0

Any thoughts or ideas on what I'm missing? Thanks.