>A blind study has a researcher doing something with a subject that is not aware of the study's true / detailled aim.
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>A double blind study has a researcher tasking another researcher to do something with a subject, with neither the subject nor the tasked researcher knowing what the study is actually about.

This is not correct and would violate principles of informed consent. A blind study is one in which the participant doesn't know if they are getting the the study drug (or procedure or whatever) or if they're getting a placebo. A double-blind study is one in which the participant and the tasked researcher both don't know whether the participant is getting the drug or the placebo. In all cases the participant must know what the purpose of the drug is and any negative effects taking it or not taking it may have.