What speeds can i expect if bonding two gigabit ethernet?

An client of mine is having speed issues on his lan and has ask me if I can find a solution.
I have read that mikrotik are able to do ethernet bonding to increase speeds.
In another post I have read that if you do a speedtest using mikrotik bandwidth server then it does not go higher that 100mb/s per Ethernet. So if I want to test gigabit speeds I must test though router not from router?

But does the connection support speeds up to 2gigabit?

Test through the router by iperf. For bonding by cpu you need each port to be individually linked to cpu. Check the Diagram of the device.