The aliases for the language Juttle occurs twice in the tuple resulting from get_all_lexers(). Here's a small snippet to reproduce
In [15]: from pygments.lexers import get_all_lexers
In [16]: lexers = get_all_lexers()
In [17]: {alias[0]: alias[1] for alias in lexers}.get('Juttle')
Out[17]: ('juttle', 'juttle')
Pygments PyPI version used: 2.7.2 (latest)