It says that I already purchased the max ammount of the 200 gems pack but I only purchased 2 in the past, so I played and reached 2000 points for nothing?
There is a limit placed on it (and most other codes) to prevent users from purchasing more than one. We placed this restriction because we were told by Hi-rez that the code should only work one per Smite Account. The limitation should prevent users from getting errors and not being able to use the code.
However, if you had purchased from the previous batch it's possible that you could buy more than one, or even more than that since the previous batch back in November or so didnt' have a limitation like the current ones.