Q: Syncing 2 phones with same device name - HELP

Hi,

I am currently using an iPhone 4S but the other day synced my old iPhone 3 to my iTunes to remove a photo album (I am lending this phone to a friend). The 2 phones have the same device name. I am now concerned that if I plug in and sync my iPhone 4S it will update to my old iPhone 3 data since that was the last thing I synced and I will I lose all my recent messages etc. Will it be ok or what should I do to ensure I don't revert to my iPhone 3 data?

Should I plug in my 4S and press back up first to save all my data? Or perhaps I should backup on iCloud or something?