Typically you only connect one screen to one displayport output connector on your ThinkPad or ThinkCentre, but in reality each displayport is capable of supporting several displays at once if they are within a certain resolution range.
Lenovo currently offers a Displayport to Displayport splitter, basically it splits displayport output signal between two EXTERNAL LCD of the same resolution and refresh rate.
The Lenovo Displayport to Displayport splitter can function in the following manners:
1. It can act as replicator for the internal LCD, so you can connect to 2 external screens and they will replicate the internal LCD.
2. It can be used in extended mode.
There are two extended modes that you can use it in.
a) Simple extended mode.
In simple extended mode, the 2 external screens will display the same image, as long as the resolution used are below the max of the individual screens.
b) Ultra-extended mode.
While in ultra-extended mode (or Mosaic mode), the 2 external screens will act as one large LCD. So basically the two external LCD will act as one large extended screen (the resolution is the sum of the 2 screens). As shown in the picture below.
For the above demonstration, i used my X1 Carbon with Dell U2410 (1920 x 1200) + Dell U2412m (1920 x 1200), to get 3840 x 1200 for the external display using the Displayport to Displayport splitter.
Note of caution, in order to get two external display to work properly, you would need to use monitors with Displayport input, otherwise you would need ‘Active’ Displayport to DVI single link adapter. Also, the external screen should be of the same resolution and refresh rate.