Usually there isn't a second 人 (rén) being reduplicated here.
人人 does mean “everyone,” but that's a different construction, and Chinese noun reduplication isn't generally equivalent to adding Spanish -ito. You may also see 小人儿 (xiǎo rénr), where 儿 is a colloquial/diminutive suffix.
You can say something like 「你看!可愛的狗狗」 and it’s “look! A cute doggy” (reduplicating 狗 gǒu). On the other hand you could say 「人人都知道她是小三!」 and it means “everybody knows that she’s (his) mistress!” (reduplicating 人 rén).
狗狗 doggy 猫猫 kitty 鸟鸟 birdie 宝宝 baby
And it kind of works for verbs too: 看看 [take a] looky
> Reduplication is sometimes employed in verbs and adjectives to enhance the effect of them.
> 胖胖的 pàng pàng de ('quite fat') from 胖 pàng ('fat')
This is the exact opposite of how I'd understand it. Saying someone is 胖 is just calling them fat (rude), but 胖胖的 is teasing, cute, chubby, etc.
gordito