Intermapper - Two Networks Appear When You Expect One

 

View the network status window (click and hold a network, or select Status Window from the context menu) to determine whether the subnet masks are the same in both ovals. If the subnet masks are different, check for a device connected to the oval with the "wrong" subnet mask with a misconfigured subnet mask.

Note: For devices polled with ICMP echoes, InterMapper tries to guess whether it should draw a link to the network that contains the IP address. If both network ovals look equally good, it may draw a link to the "wrong" one, or alternate between them.