With OpenSSH_6.7p1 under Debian/unstable, when I use ssh-add with multiple filenames to add several identities at once, the comment is set to the filename for the first identity, but not for the following ones. That is, for these additional identities, "ssh-add -L" and "ssh-add -l" output "rsa w/o comment" instead of the filename.

I suppose that the cause of this bug is that for these additional identities, the passphrase was already entered (I use the same one for each identity) and sshkey_parse_private_pem_fileblob() in sshkey.c sets the comment to "rsa w/o comment", which is rather uninformative. In this opposite case, add_file() in ssh-add.c sets the comment with:

        if (comment == NULL)
                comment = xstrdup(filename);