Kickstarter only allows the selection of one reward tier, but they recognize that some people want more than one reward level and so allow you to open a second kickstarter account (with a different email) so you can then pledge for two tiers separately from your two accounts.
Once you pledge on your first account, log out of Kickstarter and then go back to THE RANK GAME page and select the other reward tier you want. When you press the "continue" button, you'll land on a page that will invite you to create an account which you will need to do with a different email address.
After two years of play testing THE RANK GAME, we did our best to provide bundles of what people wanted most. That said, if we hear from a lot of people wanting the same combination of tiers, we may add a reward tier to meet your needs. So, feel free to let us know if you want something besides what's currently offered.