AirServer allows you to connect multiple iOS devices simultaneously. Each device would connect in the same way. For instructions on connecting an iOS device to a computer, view this article.
As each new device connects, AirServer will automatically split the screen to accommodate for each new device.
Please note, the number of iOS devices that you can simultaneously stream to a computer would depend on the strength and speed of your network and computer. There is no exact way to measure the needed bandwidth to support multiple connections, as it would vary depending on the content being streamed from the iOS devices.