/usr/lib/x86_64-linux-gnu/libCoinMP.so is in coinor-libcoinmp-dev 1.7.6+dfsg1-2build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libCoinMP.so.1.7.6
/usr/lib/x86_64-linux-gnu/libCoinMP.so.1.7.6