When you're logged in, do these unexpected test results have a yellow background such as the following example on the first two rows?
If you do see results highlighted in yellow similar to the above, what this probably means is that your internet connection goes through a shared IP address, such as a carrier grade NAT. One good example of this is cellular mobile data connections where all the devices on the network connect through a small handful of IP addresses. Even my fixed wireless ISP connection has a shared IP and I often see other user's results appear on the Results page highlighted in yellow.
You can hide these by making sure you're logged in and then click the following button at the bottom of the results page:
