Yes and no...
You cannot split an Ethernet cable with just 1 Y split, but if you are only running a 10/100 network, you can use a pair of splitters and run 2 Ethernet ports down 1 cable. This is called a cable economiser
This is because there are 4 pairs of conductors in an Ethernet cable and 10/100 only needs 2 pairs. If you are running Gigabit networks, then this will not work, as this uses all cores.
A better bet would be a small Ethernet Switch. This is an electronic device, that routes the Ethernet signal to your equipment. It has a single connection from your router and then 5,12 or more outputs for you to connect to. The switches can be had for less than £20. Here's one that I have. TP-Link TL-SG1005D 5-Port Gigabit Unmanaged Desktop Switch: Amazon.co.uk: Computers & Accessories
That being said, your Superhub has 4 outputs anyway, so can you not just run separate cables?