Does it need to resend my luggage in PEK airport?

ICN-PEK-JNB-MPM is my flight .

Normally when i send my baggage, it proceeds to final destination automatically.
But i've heard that I should take my luggage in PEK and resend to MPM when i transit in Beijing.
is that right information?

My First airline is China Air (ICN-PEK) and Second is South Africa Airways(PEK-JNB-MPM)

also i need terminal information in Beijing becuz my transit time is too short(just 3hours).
Thankyou.