Synching 2 3Gs iPhones to one iTunes account on one computer

Question

I have a few questions regarding synching two 3Gs iPhones with one iTunes account on one computer.
I had synched both phones (mine and my wifes) to our desktop computer but saw that apps were being placed on both of our phones and contacts were being added to both and duplicated.
1. If I try to synch my wifes iPhone to a her laptop with a new itunes account and it asks about erasing the data, will it get rid of the photos and contacts? I have looked this issue up and no one really seems to know.
2. If I try to synch both iPhones to the desktop with the original itunes how do I avoid the issues of transposing apps, contacts being added to both? Several answers out on the Net say to make two seperate accounts. Does that mean two seperate "iTunes" accounts? Or two seperate profiles on the desktop computer.
The main reason I need to do this is because my wifes iPhone is about two or three firmware updates behind. I would like to update her firmware and back up all of her apps and contacts. I am backing up her photos to Shutterfly just in case, because if something happened to those I might not be around to see iPhone 5. hahaha j/k
Any help would be appreciated.

Answer 1

Welcome to the discussions,
1. If you manually backup your wife's phone before you sync for the first time to the laptop, you can save all data and settings of the phone and restore from that backup again after the initial sync.
Here's how to backup manually:
Set up the same iTunes account on the laptop, disable autosync in iTunes/Settings/Devices.
Connect the phone, right click on it in the device list and choose "backup" iTunes will backup your phone without syncing.
Transfer your purchases the same way, to copy apps and purchased media to the new library.
When you connect your phone for the first time, all media content will be erased. But you can restore your settings and app data from your manual backup afterwards.
Don't forget to set up at least one contact and event on your new computer to be able to merge calendars and contacts when you sync the phone for the first time.
About backups and what's saved: http://support.apple.com/kb/HT1766
How to back up and restore: http://support.apple.com/kb/HT1414
How to download apps for free again: http://support.apple.com/kb/HT2519
2. If you're syncing both phones on one computer, either create a second user account on your computer, log in and do the same manual backup process as described above, or, take the time to set up each phone individually, including the settings for calendars and contacts, which apps to sync, etc.
iTunes will remember the settings for each phone and you'll only have to do this once.
You can only use apps on different devices if you're using the same account you did at the time you bought them.