Hi there
First of all "web_page" is just a built in share that shows up on the 323. It contains a link to the D-Link website, so don't worry about that.
Secondly, you should only see one "Volume" (Volume_1). If you have a "Volume_1" and a "Volume_1-1" you have created another share within the NAS's web interface to the same location, which is why you see your file under both shares. This has nothing to do with the fact you are running in a RAID-1 setup. RAID-1 simply means your data is duplicated over two disks, but the NAS will only give you access to one of them. Should either drive fail, the other will take over automatically.