Fixed the emoticon addition when it already exists

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Related tickets | #89
| License       | MIT

- [ ] Reply to the question below

The behavior described below is correct?

```yml
emoticonA: #1 from imports
    smilies: [ :a:, :aa:, :a2: ]

emoticonAB:
    smilies: [ :a:, :b: ]

emoticonA: #2
    smilies: [ :a2: ]
```

same as:

```yml
emoticonA: #1 from imports
    smilies: [ :aa: ]

emoticonAB:
    smilies: [ :a:, :b: ]

emoticonA: #2
    smilies: [ :a2: ]
```

Smiley list resulting: `[ :aa:, :a:, :b:, :a2: ]`