Why create multiaccounts to buy a Facebook page? Yes, Yes and Yes. He's trying to trick people.
Be careful and always ask to send you a private message on the forum before the transaction. ((Unfortunately, there is no correspondence left from telegram)
If his intention was to scam you then he wouldn't send you a pm from his main account. Why would he expose him self?
People create alts mainly for privacy reasons. Probably he is using this alt so bought fb pages can't be linked to his legendary account.
I don't see anything wrong or suspicious here, unless am missing something!