Photos can't be transferred from your computer to the iPhone's Camera Roll. The Camera Roll is for temporary storage for photos and/or videos that were captured by your iPhone's camera, and for photos saved from a recieved email, from a recieved MMS, or from a website.
Geotag data included with a photo remains with the photo. With a Mac if you use iPhoto for importing photos from a digital camera including from your iPhone and for photo storage and management on your Mac, import the photos from the Camera Roll on the iPhone with the photos and transfer the photos to the other iPhone via the iTunes sync/transfer process.
I can't begin to thank you enough for the Photosync idea. My wife and I took a "trip of a lifetime" to Europe and backpacked for 29 days. I bought a new iPhone 4s when we got back, and just added the pictures to my new phone. Didn't worry as they were on my computer. Computer then crashed and I was told I lost the geotagging as there was NO WAY to get back the pictures from my iPhone to a computer. We had several amazing hikes that I wanted to know exactly where we were.
I've tried 4 other programs that were supposed to work... no dice... just tried photosync and everything is there. All geotagging and everything... pretty fast transfer too!
I'm going to stop before I sound more like an informertial. Thanks again. I hope Apple reads this and doesn't tell someone else that there is NO WAY it can be done!