Installing the latest version of libpcap & libpcap-dev

In my docker container I run the following command to install the lib pcap: apt-get install -y libpcap-dev When I run apt list --installed I see this weird output:

libpcap-dev/oldstable,now 1.8.1-6 amd64 [installed]
libpcap0.8-dev/oldstable,now 1.8.1-6 amd64 [installed,automatic]
libpcap0.8/oldstable,now 1.8.1-6 amd64 [installed,automatic]

Does anyone know why it shows "oldstable" and then "now"? Also, how do I force the installation of the latest version of libpcap and libpcap-dev? I've been searching all over but can't figure it out. Thanks! P.S. I'm doing the installation inside a Docker container.