You can sync as many Exchange profiles with the Android version of Touchdown as your device can support. However, only one account will be active at any time (pushing or polling). To create new profile, please click Menu/More/Profiles on the main screen, and add a new profile. Long press on any profile to see options such as moving its data to SD card, etc. Once you create a new profile, a new button in the home screen will appear to allow you quickly switch profiles.
Unfortunately Touchdown for IOS does not support profiles at this time.
NOTE: Profiles are not recommended if you are using an Mobile Device Manager (MDM) such as MobileIron or Airwatch, to connect to your server. This can cause issues with your connection to your Exchange server.