MacBook Pro multiple displays mirror error

Hi everyone!

So I've got two Samsung SyncMaster940BW monitors that I've previously used on a Windows desktop.

In order to connect these to my MacBook Pro (13-inch, Mid 2012), a web store advised me to use the following setup:

MacBook Pro > Mini Display Port connected to DVI Adapter > DVI Adapter connected to a DVI Splitter > Both DVI splitter ends each going to a single monitor.

- Now everything is working fine, the only thing is that my external monitors are both displaying the same screen.

- Also, in my Mac display settings my MBP only seems to detect 1 external monitor.

Is there something I'm doing wrong/is there a way to solve this?

Would it for example be a solution to tell my MBP to shut down it's own laptop screen and move that screen to one of the external monitors? I'm not really using my MBP's screen.

Thanks in advance!