The system is designed from the ground up for maximum flexibility. There's no set limit to the number of mobile devices that can pair with a sensor or access the same Gateway and cloud account. Many users have only one mobile device, but some business and other customers have many. Here's how to make it work:
Without a Gateway
If you're not using a gateway and would like the same sensor on another mobile device, just re-add it to the second mobile device, just as you did the first. Repeat for any additional mobile devices. In this case, if you have custom settings like alerts, you'll need to manually re-enter them on each mobile device.
With a Gateway and SensorPush Cloud
To use the same Gateway and cloud account with another mobile device, you don't need to (or want to) re-add each individual device. Just tap the settings icon in the top left corner of the main devices screen. Near the top of the next screen you'll see a button to log in with the account's username and password. After you log in, the account's sensors, gateways, configuration and sensor data will automatically load into the app.
It's far less common, but you can even use the same sensor with two or more different SensorPush cloud accounts. Just add it to a mobile device from each account and be sure the sensor is in range of a SensorPush G1 WiFi Gateway belonging to each. The rest will work automatically.