Every DHS survey selects an independent sample of households. It is theoretically possible that the same household or person may be selected more than once, but in practice the chance of being chosen more than once is negligible. DHS does not maintain names and addresses of respondents to previous surveys so there was no way that respondents in a previous survey could be excluded in the next survey. In any event, there would be no reason to do so. The chance of the same respondent being chosen in two different surveys depends on the sample size of the survey and the population size in the eligible age range in the country. On average, the probability of being chosen more than once would be less than 1 in 1,000,000.