It’s funny you mention our region issue, as I also only ever remeber it as Halloween Harry, looking into it the first version does appear to be Registered HH.
I’ve just checked the versions on here https://www.classicdosgames.com/game/Alien_Carnage.html and the 1.1 Reg is all four missions with the title screen as HH.
And in the ordering info it confirms its the registered version but also lists an Australian distributor for more orders, so it was clearly distributed here from the beginning!
