If you want to use two Cam Linkson one computer at the same time, your computer will need to have two separate USB 3.0 Root Hubsor Host Controllers.
Not every Desktop computer has two separate USB 3.0 Root Hubs.
Many Laptop computers do not have two separate USB 3.0 Root Hubs.
The following article discussed where you can find out how many USB 3.0 Root Hubs your computer has.
PCs and USB 3.0 Root Hubs
Macs and USB 3.0 Root Hubs
You can use the System Informationapplication on your Mac to find how how manyUSB Root Hubsare installed, and whether they use USB 2.0or USB 3.0.
Here is a screenshot showing a Mac with two separate USB 3.0 Root Hubsand a Cam Linkattached to each one:

Here is a screenshot showing a Mac with two separate USB 3.0 Root Hubs, but two Cam Linksare attached to only one USB 3.0 Root Hub. This will cause problems, or not work at all:

Here is a screenshot showing a Mac with only one USB 3.0 Root Hub. Only one Cam Link can be attached:

Not every Desktop computer has two separate USB 3.0 Root Hubs.
Many Laptop computers do not have two separate USB 3.0 Root Hubs.
The following article discussed where you can find out how many USB 3.0 Root Hubs your computer has.
PCs and USB 3.0 Root Hubs
You you can use the free USBtreeviewutility to examine your PC to find information about USB Root Hubs:
https://www.uwe-sieber.de/usbtreeview_e.html
Macs and USB 3.0 Root Hubs
You can use the System Informationapplication on your Mac to find how how manyUSB Root Hubsare installed, and whether they use USB 2.0or USB 3.0.
Here is a screenshot showing a Mac with two separate USB 3.0 Root Hubsand a Cam Linkattached to each one:
Here is a screenshot showing a Mac with two separate USB 3.0 Root Hubs, but two Cam Linksare attached to only one USB 3.0 Root Hub. This will cause problems, or not work at all:
Here is a screenshot showing a Mac with only one USB 3.0 Root Hub. Only one Cam Link can be attached: