Option parser: when value is the same as full parameter name

Part of command line model:

```
[Option('o', "output", Separator = ' ')]
public IEnumerable OutputPathsList { get; set; }

[Option('d', "output-dir")]
public string OutputDir { get; set; }
```

And part of command line:
`--output-dir output -o :loop :magic_value`

if 'ouput' value is the same as full parameter name "output" I'll get empty OutputPathsList.