With the ever increasing popularity of the iPhone, it's be becoming more and more common for households to want to connect multiple iPhones to one computer. Thankfully it's not that hard to do but there are some tips that will make it easier to connect two iPhones to one computer.
To make it easier, it's best to use the same iTunes store account on both iPhones. The reason being is that if you use a different account on both iPhones, you will only be able to back up the apps of one iPhone since only one iTunes account can be logged into the computer at any given time. The work around is to sign in and out of iTunes each time a different person syncs their iPhone but that is extremely tedious. Make it easy on yourself and use the same iTunes account for both iPhones.
Also, before syncing either iPhone, create two address book libraries. That way you can sync one to each iPhone to bring in the contacts. This step is for Macs only.
The next step toward using two iPhones on one computer is pretty easy. First connect the first iPhone to the computer you want to use. Once connected, go through the various tabs under the iPhone screen in iTunes and select what you want to sync. This includes music playlists, photo albums, apps, and other items.
Now, disconnect the first iPhone and repeat the above step for the second iPhone. iTunes will recognize each device as unique and store the settings for each. You are now ready to use two (or multiple) iPhones on one computer!