Backers can only choose one reward tier per pledge and per email address (Kickstarter account).
However, should a backer decide to pledge more than one reward, the backer has to use a different email address than the one used for the first pledge.
Kickstarter - Pledging more than once
Backers can only choose one reward tier per pledge and per email address (Kickstarter account).
However, should a backer decide to pledge more than one reward, the backer has to use a different email address than the one used for the first pledge.