Ancient Greek arguably has a dual indefinite article tiné. Literally it means "some [two things]", and is unrelated to the numeral "two".
To elaborate a bit more: Ancient Greek didn't have mandatory indefinite articles during the Classical period, but the indefinite correlative tis was in the process of grammaticalizing into that niche. The dual wasn't particularly productive (or common) by this point, mostly showing up in fixed expressions like "two eyes", but tis still had a full declension pattern, including dual forms.
(Note: tis is specifically the Attic dialect form; other dialects had kis or sis.)
Eventually, the singular forms of tis-as-indefinite-article were displaced by forms of hen- "one"; the plural was unaffected, and the dual had died out completely by that point. But if the dual had survived into Modern Greek, it would presumably have an article based on tiné or on dyo "two".