Are multiple accounts per household allowed?

Multiple accounts per household are allowed but in order to avoid duplicate participants in a study, we have a mechanism in place that allows only one person per household to take part in a particular study. For example, if person A and B are from the same household and person A participates in Study X then person B will automatically be ineligible for Study X. Person B will only be eligible for studies that person A has not completed and vice versa.