There is truly an advantage to adding multiple NIC cards to a computer. It won’t speed up a single internet connection but it can help with loss of signal, detecting access points, transferring information to and from computers.
When adding a second NIC card to a computer, you can highlight both by holding down the CTRL key and clicking on them and then right clicking to bridge the connections so they act as one…this can allow you to bridge a wireless network to a wired network.
Two nic cards on the same network can allow for load balancing.
Dual Wireless Cards