Today I filtered a beer from "FV05" to "BT01". The beer on FV06 was one number off from the beer in FV05. I inadvertently sent the wrong beer in the filter step. OBeer let me filter the "wrong" beer using the right batch number for the filter step. However it overwrote the batch number on the wrong beer. Thus leaving me with two batches in two different tanks with the same batch number.