Chabad.org — English translation + Rashi
Torah Temimah (Pesachim 93a): the doubled “ish ish” includes additional cases within individual deferral.
English: One might have thought that only those tamei by a nefesh and those on a distant road offer the second. From where [do we include] zavim, metzoraim, and those who had relations with niddot? The verse says: “A man, a man.”
Inclusion via doubling — the repeated noun expands the circle of those who may claim the second month.
The individual path of Pesach Sheni is open to every Jew who meets the stated conditions.