Question on performing missed salah or prayers?

Asalamualaykum, I missed prayers(QAZA) for some years.so now i'm able to perform the missed salah.can I perform QAZA salah every time along with the actual day prayers(eg:If i pray for fajr 2 times,one is the actual prayer and the other is qaza) OR can I perform the whole qaza prayers(5 times) at a time???? please help.......