You cannot use two or more cameras to create one model at the same time. While you are scanning there is a 1:1 relationship between an iPad/Capture app and a physical Matterport camera.
However, if your camera malfunctions you can connect the same iPad to another Matterport camera.
Similarly, if your iPad fails you can use a new iPad with the same camera. Of course, you will have to download the Matterport Capture app, create a new model, and start over.