Yes, you can safely connect your laptop charger to your laptop at the same time a Plugable USB-C or Thunderbolt docking station is connected.

To expand further, all Plugable USB-C or Thunderbolt docking stations use a protocol known as USB Power Delivery (aka USB PD) in order to provide power to the host computer.

An external device using USB PD (such as a docking station) will provide power to the host computer only if the host computer requests it. 

In cases where there are two external devices that can potentially provide power connected to the laptop, the host laptop will automatically determine the preferred source of power from which to charge.

If your laptop’s power adapter provides a higher rate of power than the Plugable docking station, then the laptop will only charge from the laptop’s power adapter and the Plugable docking station will not provide any power.

For example, let’s say your Plugable docking station can provide up to 96W of power to charge the host laptop. Let’s also say that the power adapter included with your laptop can provide 140W of power.  

In this specific case, via the USB Power Delivery protocol the laptop will automatically determine that the 140W power source is preferable to the 96W power source. As a result, the laptop will only accept power from the 140W power source and the docking station will not provide any power.