I've only tinkered with CRDTs, but one common theme in those applications is changing the data structure to accommodate the CRDT.
In your example, that might mean changing the single "phone number" field to many "phone numbers", so that merging the two writes results in a customer record with two phone numbers. This preserves the data, but pushes conflict resolution (which number should be used?) out into the consumers.
In your example, that might mean changing the single "phone number" field to many "phone numbers", so that merging the two writes results in a customer record with two phone numbers. This preserves the data, but pushes conflict resolution (which number should be used?) out into the consumers.