This message was posted on behalf of Intel Corporation
You mentioned the laptop has Intel® Graphics 4400, the specifications of the laptop said the graphics controller on it is Intel® HD Graphics 520, still, the latest graphics driver version for both controllers is 4501, you can always try that driver in order to fix the problem:
The reason why this configuration is not working could be related to the splitter, since the signal came just from one source, and then that one signal gets split in two, some features might not work they way it should.
Another option might be to try a different splitter, but the results might be the same, since the source is still only one.
When the laptop has a display port, there might be different options to set up a dual display, like the one called daisy chain, which is basically attached one monitor to the other, but, unfortunately based on the specifications, the laptop has no display port:
Any questions, please let me know.