DynamoDB batchWrite, different hash key, same range key. but got Provided list of item keys contains duplicates

I got table key schema like this:

		KeySchema: []*dynamodb.KeySchemaElement{{
				AttributeName: aws.String("address"),
				KeyType:       aws.String(dynamodb.KeyTypeHash),
			}, {
				AttributeName: aws.String("tx_id"),
				KeyType:       aws.String(dynamodb.KeyTypeRange),
			}},

write record like this:

	for _, storeKey := range t.StoreKeys() {
		mainItem["address"], err = dynamodbattribute.Marshal(storeKey)
		if err != nil {
			return err
		}
		mainTxPut := dynamodb.PutRequest{
			Item: mainItem,
		}

		writeRequests = append(writeRequests, &dynamodb.WriteRequest{
			PutRequest: &mainTxPut,
		})
	}

but when using different address value, same tx_id, i got err:
ValidationException: Provided list of item keys contains duplicates

Beacuese hashkey is different, i should be using a different key. So why dynamodb tells me that my key is duplicated?

I'd strongly encourage you to add some logging to ensure you have no duplicates in a batch. When you get an exception simply log the batch for inspection.

Items must have the same primary key to be duplicates.