Merge: variable does not uniquely identify observations in the master data

Hi everyone,

I have a data with a variable household ID that does not uniquely identify observations. So a single household has multiple members. I want to merge it with another data that has the same household ID but it uniquely identifies observations. I have merged the using data to the masters data with the following command:

merge 1:m HH_ID using education

where education is my using data with observations not uniquely identified. It worked and now I have a merged dataset. But now there are some observations which are not matched and which only exist in the master data. So are these duplicates? Should I drop them and only keep the matched observations?