Why does my laptop have two graphics cards?

The point of the 2 is to enable your laptop to use a lower battery consumption when you don't need the power of a high-spec GPU.

Most of the things you do on the laptop probably don't need high-spec graphics.

There should be an application running that associates applications with each graphics card. So if you are not bothered about battery life, simply make everything use the dedicated card rather than the Intel one.

Advantages of two GPU is improved power consumption management along with performance. The GPU's are connected by a SLI bridge which will decide which graphics card have to be used for a particular task to be performed. it will either use single/individual GPU or both by evaluating the task you are running.

It is possible to change the GPU of your choice in order to solve any issues with multiple GPU's. Options are available in Nvidia control panel