For those of you interested in having two DayZ accounts on one computer (usually those who share a computer), there is a way to have two DayZ accounts. Using two different steam accounts each of which owning the necessary games should work, and below I will explain how. You can do this with ONE copy of Arma 2: Combined Operations and ONE spare copy of Arma 2: Operation Arrowhead. You do not need two copies of Arma 2 itself as it goes by the CD key of the Operation Arrowhead extension.
It looks complicated, but it's pretty straight forward. If you are unsure on what you are doing, just make sure you do one step at a time.
1) Install your first copy of Arma: OA from one steam account (If you already have one working copy, you have done this step)
2) Run "regedit".
3) Locate "KEY" from "KEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Bohemia Interactive Studio\ArmA 2 OA" (It will be a REG_BINARY type that looks like '00 aa 1b.....', it's covered by a red box in the image in order to protect my account)
4) Click on Key to highlight it and File -> Export -> (Save with any name in any location you remember). This will export a copy of the key for your first copy of Arma 2: OA
5) Logout of your first Steam Account and Log into the second steam account which has it's own Arma 2: OA installation. (If you are using a disk/hard copy installation, just install the second disk)
6) Launch the Arma 2: Operation Arrowhead game from the second steam account. Close the game once it's fully loaded. That should trigger the seriel key (the one you located above) to change to that of the second copy of the game. However, if the registry key is still the same you will have to uninstall the game completely and reinstall it from the second Steam account in order to change the seriel key.
7) Relocate the registry key from above and, export it again and save it as a new file (If you did step 6 correctly, the registry key will be different to the one you exported in step 4).
8) Each key is a different account. To change the key in the registry, just double click on your saved registry file and the key will change. There will be no need to log in/out of steam if you have changed the key manually by double clicking on the file and accepting the changes. You can repeat this as many times as you like, provided you have enough Arma 2: OA seriel keys. Similarly, you can send your registry files to friends to let them play on your account!
Each different registry key will be a different DayZ account. I recommend using two different steam accounts to be sure both keys are saved (somewhere) just incase. This is a perfect solution for siblings/couples that share computers but would like to have their own DayZ experiences. If you wanted to, for example, access your dayz account from your friends PC, then all you would need to do is open the registry file from the pc you want to log in from (remember to save their key first to avoid hassle!). If you experience any issues, opening steam and launching Arma 2: OA will reset the registry entry with that Steam User's key.
If this helped you, please comment to reassure others and help to keep the topic bumped.
I accept no liability if this didn't work for you, however I spent a while trying to find out how to do this and felt it would help the community if I explained the process to you.
FAQ - Read this before posting for help
Edited by DocTolly, 20 September 2012 - 12:42 PM.