[OS X TeX] \hhline{----~}\hhline{----~} vs \hline\hline

[Alain Schremmer]

\hline\hline gives

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but \hhline{----~}\hhline{----~} gives

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Is there a way to separate the two \hhline{----~} the way the two  
\hline are?

Hopeful regards
--schremmer