nm results with trailing numbers in symbol names

Question

I have an empty program:

int main(int argc, char **argv)
{
    return 0;
}

When I run nm path/to/exe --format=sysv I get numbers in the symbol names e.g file_mtx_85 and free_fn_89.

With different program I can get duplicates like var_101 and var_102. I think the duplication is because I have more than one symbol with that name, but why do I get numbers in the symbol names and what do they mean?

I'm compiling with Xtensa compiler.