Visa Free Transit BOS-PEK(~48 hours)-HKG-PVG (~48 hours)-BOS

If I fly BOS-PEK-HKG-PVG-BOS on one round trip ticket, can I receive Free Transit at both PEK (~48 hour layover) going to Hong Kong & PVG (~48 hour layover) on the return? I am unsure if I can receive free transit twice on a round trip ticket.