>OK, so you're saying explicit or implicit logoffs didn't always occur. It looks like you're looking for evidence of "simultaneous" activity, the idea being if such is found, they must be different people. Simultaneous activity could be things like:
>
>- hits from the 2 different IPs/accounts within a very short time period (e.g. a few seconds)
>- interleaved hits over some reasonable time period i.e. not just from one account or the other
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>But, if I'm correctly interpreting what you've been saying so far, you have seen neither of the above for Kevin and "Grover", so you believe it is one person, first paying attention to one account, then to the other.
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>IMO that's a reasonable interpretation. However, I agree with Tracey - I think it would be a good idea to run your analysis for "Grover" vs. other active members, and also for Kevin vs. other active members. If any of those analyses raise the same flags, then the behaviour may not be unique, or your analysis algorithm may be flawed (or both).

If there would be a third person involved, than this would be worst as it would mean that three persons decided to prepare a scenario to cause trouble at a precised time frame. If there is a third one, I haven't found it yet.