Region 3664's Past Return

Sunspot region 3664 came and went, then 3697 came and went. There was what came next, and I just went ahead and asked the SWPC about it and here is the response I received,

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The majority of the M-class activity that was assigned to Region 3723 occurred just as it was rotating onto the East limb so that activity was assigned to it at that time. It took several days to truly see the magnetic separation of different Regions and 3727 was eventually separated out. That complex of Regions was fairly intertwined and the plage area was combined. The reports of old 3664 (and 97) returning and continuing to be active were written largely before it was separated out. It is possible to make the argument based on longitude that 3723 is new and 3727 is the returning region; and it is also possible to argue that 3727 was responsible for the flare activity but at the time, they were a combined Region numbered 3723.