Arabic has dual subject pronouns. I wonder if the concept developed independently or if there was any influence somehow?

Arabic is on the Semitic branch of the hypothesised proto-Indo-European language, which has dual number: https://en.wikipedia.org/wiki/Dual_(grammatical_number)

So you'd expect to see languages from western Europe to south Asia that either have the dual concept, or have an attested ancestor that did.

	▲	eigenspace an hour ago \| parent \| next [-]
		The Semitic language family is not part of the proto-indo-european language family. It's from the Afroasiatic family https://en.wikipedia.org/wiki/Semitic_languages https://en.wikipedia.org/wiki/Afroasiatic_languages
	▲	another-dave an hour ago \| parent \| prev \| next [-]
		Within Indo-European languages, Irish has the concept of the dual. It's used with things that come in pairs like "mo dhá láimh" - my two hands. Interestingly, to say one-handed you'd say "leath-lámh", where _leath_ means half, so half the <thing that's usually one of a pair>.
	▲	mathieuh an hour ago \| parent \| prev [-]
		Semitic languages are Afroasiatic, not Indoeuropean.