You don't have to buy the app twice to get it into each iDevice. If you have different Apple account in second iPhone or iPad, check our other guide describing how to install the app to second device.
Then you can use the app. Start by selecting which device you want as Baby Station and which as parent station
Put device with baby station to the child's room. On second device select parent station. Then it will found available baby stations and you can start monitoring.
You now hear every noise from child’s room
For more information visit www.babymonitor3G.com