If you have more than one device, you can log into your account on both, but you can't share devices with other shopkickers or collect kicks on more than one device at a time.
You'll get a notification when you log in on a second device that you have done so--this is just a reminder. You can still do your regular shopkicking, just remember that you can only collect kicks on one device at a time, so you only need one when you go shopping. Also, you can't share devices with other shopkickers, meaning no one else is allowed to log into their shopkick account on any of your devices at any time.
Please note that shopkick does not support Android tablets at this time. While some iPads are compatible with shopkick, scans and walk-ins may be harder to pick up on an iPad than on a smart phone. For scans, you may have to hold the item a bit more still than you did before, and it can take a while longer for the iPad camera to get focused and get a good read -- please be patient. For walk-ins, we do recommend using your smartphone, but if you are using the iPad and having trouble, restarting in the store can really help.