Multiple Users With Same Log In Showing Up, Error?

Each time I log into our www.ads-software.com site when I go to the WP Security Plug in > User Log In > Logged in Users I see the user account I have logged in with displayed twice. Once with the correct IP address for the computer I am on and once with another IP address. I do not believe someone else is logged in elsewhere. And when I force log out the IP address that doesn’t match my own it will actually force log me out. So I assume from this both logins are me at the same time. I should also add that the second IP address, which doesn’t match mine is the same each time I have done this on my computer. I can repeat this situation with any of our website user accounts.

Why is this happening, and what is that second IP address from?

Thanks for the help!