The fact the memory is dual sided has nothing to do with the amount of RAM on it. I could show you some old 512KB, 1MB, 32MB, etc... RAM that was double sided. You have to read the stencil on the stick, if there is one, to determine what size it is.
Short of a stencil on the stick, you can look at the packaging the RAM came in to make sure they sent you 2x1GB and not 2x512MB sticks. And, even then, if the package says it's 1GB sticks and they size out to 512MB, that's usually a good indication of mis-packaged sticks or it's just plain BAD.
Also, your motherboard has BIOS to tweek the RAM. Here's what I found about it:
The K8T Neo2-F v2.0 provides 2 DIMM sockets using 184-pin DDR with a total capacity of up to 2GB. You can install DDR 266/333/400MHz Memory. (Due to the High Performance Memory design, motherboards or system configurations may or may not operate smoothly at the JEDEC (Joint Electron Device Engineering Council) standard settings (BIOS Default on the motherboard) such as DDR voltage, memory speeds and memory timing. Please confirm and adjust your memory setting in the BIOS accordingly for better system stability.)
Have you been into the BIOS to see what it says in there? Did you change something that might make the RAM not be recognized correctly?
