Docker 2 ip addresses

my host is ubuntu server
i installed docker
i created 1 new docker network - bridge
i run 3 containers attached to that new network. 1 container contains a webserver.

When I netscan my network 2 ip-addresses are associated with this webserver. One from my host and one new ip address.

How is that possible? The webserver is indeed reachable from the 2 ip-addresses. Can someone explane this, please?
The 2 ip addresses have the same MAC address.

Regards, Maarten