libdtk6core-dev is declared Multi-Arch: same, but fails to coinstall.

The file /usr/share/qt6/doc/dtkcore.qch is shared by libdtk6core-dev
version 6.0.50-1+b1 as present in forky and version 6.0.50-2 as present
in 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