GROWLr does offer the functionality of sharing one profile across multiple devices.
Make sure you have an email and password loaded in the fields provided in your profile settings.
If you would like to share your profile on a separate device:
Load GROWLr from the App Store
Open and choose Log In, then enter your email and password.
You will now be able to use this device with your account.
Messages will only appear on the device you are using at the time.
Notifications will go to the last device that was in service.