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No it is not the same as a visual registration check. Its purpose is to be able to limit registration to only those whom you want and/or to place them in appropriate groups you choose. Visual registration check just ensures nobody can spam the registration process. This can act as a solution for the problem if you require all registrants to enter in a registration key, since it would take an incredibly long time for someone to brute force hack a 20 character key. However, the difference is that the user must know the registration key beforehand. Its uses are meant for situations such as customer service, organizations, etc.