Maybe this was fixed in newer portage tree, but for me there are two binaries with same md5 hash that are not symlinks: 6bb4ccfc949a7f48fba2fd3f67739113 /usr/x86_64-pc-linux-gnu/gcc-bin/13/x86_64-pc-linux-gnu-g++ 6bb4ccfc949a7f48fba2fd3f67739113 /usr/x86_64-pc-linux-gnu/gcc-bin/13/x86_64-pc-linux-gnu-c++ Same goes for gcc 12. There is also possibility g++ is linked or even compiled twice.
Same on armv7
It would help to know which date/commit you're at of ::gentoo.
~$ ls --inode /usr/x86_64-pc-linux-gnu/gcc-bin/13/x86_64-pc-linux-gnu-?++ 5476725 /usr/x86_64-pc-linux-gnu/gcc-bin/13/x86_64-pc-linux-gnu-c++ 5476725 /usr/x86_64-pc-linux-gnu/gcc-bin/13/x86_64-pc-linux-gnu-g++
Huh. Hardlinks indeed. Didn't expect them.