I think EB spelled Pyrrhus' name wrong

[L'Impresario]

Or when there is a double rho, but Teleklos already said that

Yep, the double rho usually appears in composite words, where the second one begins with "ρ" such as "παραρρέω", "απορρίπτω", "ισόρροπος", "παραρρήγνυμι" etc.

And while we 're at it, I think I saw a greek building containing the word "archon" (άρχων) in the genitive declination which should be "archonta" (άρχοντα) but instead is "archou".
Am I missing something?

EDIT: Oops, got that "s" out;)