libnet1-dev is declared Multi-Arch: same, but fails to coinstall.

The file /usr/include/libnet.h is shared by libnet1-dev version
1.3+dfsg-2 as present in trixie and version 1.3+dfsg-3 as present in
forky|unstable with varying content.

Please ensure that shared files have bit-identical content across
architectures, move architecture-dependent files to
architecture-dependent paths or remove the Multi-Arch: same field.

Kind regards

Helmut Grohne