We are changing the name of the table that stores offset. So in new table offset value becomes 0. But we should use old one - to avoid processing whatever is in kafka from the beginning (which will also cause duplicate processed records).
NOTE: We didn't notice that when doing tests however, which is strange. I.e. nothing is processed twice.. Which would be expected due to this bug. Only explanation - the MetricValue in Kafka topics, its class was changed (package) - that could cause not decoding old metric values.