duplicate CVEs that are present both in stdin and on cmdline are not removed

i.e.:

```
$ rhsecapi -0f bugzilla CVE-2016-9079 <<<"CVE-2016-9079"
[NOTICE ] rhsda: Found 1 CVEs on cmdline
[NOTICE ] rhsda: Found 1 CVEs on stdin
[WARNING] rhsda: Stdin redirection suppresses term-width auto-detection; setting WIDTH to 70
[NOTICE ] rhsda: Valid Red Hat CVE results retrieved: 2 of 2

CVE-2016-9079
  BUGZILLA : 1400376

CVE-2016-9079
  BUGZILLA : 1400376
```