How did it work out?
I have used multiple blackmagic capture devices before - although not identical ones
these little guys are useful, connects via usb-c/thunderbolt: https://www.blackmagicdesign.c...
depends how many ports the macbook has. if its a new macbook pro you have 4 usbc/thunderbolt ports. what I used to use was an old Ultrastudio thunderbolt plus an old Intensity Shuttle USB3 on a 2015 mbp. Never had issues (well... there are always issues, but not in terms of having multiple blackmagic devices). the blackmagic utility is very useful in letting you configure each device separately.
probably too late but hope this helps