Kids grow up speaking 8 languages. There are a few who only learn one. Mostly us English speakers.
No it will be a lot harder learning two.
My shift partner spoke several languages as most of the Gurkhas do, they start with the native dialect, then Gurkali, then Hindi and English. Over the years he's picked up Cantonese from being posted to Hong Kong and a couple of other languages including Fijian 'pidgin'. He chats to one of the Sikh soldiers who speaks Hindi, we have a lot of bilingual people here, not all immigrants we have plenty of Welsh, Gaelic and Cornish speakers too.