If i had multiple residencies in the same city and kept one of them clean of all paraphernalia/incriminating info so as to have shit sent there and then a CD happened, would LE find out about my other residency? Would they be able to obtain a warrant to both by the time the CD was performed?
It's safe to assume yes. The whole point of a drop is to disconnect yourself personally from any contraband that is being shipped to you. If you have multiple residences then you personally are the common denominator.
Think about it like this, if you had drugs at one residence and they did a CD at another, would you be worried? I sure would be.