I believe the answer is, as always, “It depends.” It should not be necessary to call identify on both Sources except in the case that each Source is a “System of Record” (SOR) for disparate datapoints about a user. If each Source is only tracking user interactions, it is not necessary to make an identify call, only track calls.

For example, if Source “A” is the SOR of a user’s favorite store category, “Board Games”, and Source “B” is the SOR for user geolocation. In that case, Source “A” and “B” must each make identify calls to update users’ profiles with favorite store category and geolocation data.

Does that give you a clear picture, Hannah?