/diy/ - Do It Yourself

How does coax splitter signal attenuation work? For example, if pic related is -5db per output does that mean each output is -5 individually (so each device will only get a -5 penalty), or is it -5 per each port in use on the network as a whole (so 1 port is -5, with all 4 it's -20)?
If you have say a modem and 2 DVRs, and of course the modem should have the highest signal possible, can you split the source once for the modem then split it again for the DVRs and give the modem less loss, or is it all cumulative?