No warning or error when allowing an application profile and the same port

[Dan Dascalescu]

My distro comes with an /etc/ufw/applications.d/nginx like this:

```
[Nginx HTTP]
title=Web Server (Nginx, HTTP)
description=Small, but very powerful and efficient web server
ports=80/tcp

[Nginx HTTPS]
title=Web Server (Nginx, HTTPS)
description=Small, but very powerful and efficient web server
ports=443/tcp

[Nginx Full]
title=Web Server (Nginx, HTTP + HTTPS)
description=Small, but very powerful and efficient web server
ports=80,443/tcp
```

If I run `ufw allow 'Nginx Full'`, then `ufw allow 443`, I'll effectively have 443 allowed twice. This feels wrong - ufw should warn me that perhaps I meant something else.