Lambda function triggering more than once

Question

I am trying to create the following architecture on AWS. AWS architecture

I have 3 devices connected to Iot core:

-Thermometer

-Air conditioner

-Lambda function

Thermometer should send the temperature every 5 seconds to the Core, then the telemetry is sent to Kinesis stream and to Kinesis Analytics.

Here is the query who groups data arriving in 60 sec windows.

Query :

CREATE OR REPLACE STREAM "TEMPSTREAM" ( 
   "avg_temp" BIGINT NOT NULL, 
   "dateTime" TIMESTAMP,
   "sender_id" VARCHAR(64));

CREATE OR REPLACE PUMP "SAMPLEPUMP" AS 
INSERT INTO "TEMPSTREAM" ("avg_temp","dateTime","
    SELECT STREAM AVG("temperature") as "avg_temp",ROWTIME,"sender"
    FROM "SOURCE_SQL_STREAM_001"
    GROUP BY "sender",STEP("SOURCE_SQL_STREAM_001".ROWTIME BY INTERVAL '60' SECOND)
    having AVG("temperature")>=27;

It produces the Average of the temperature then sends it to Lambda function.

This function just connects to IoT Core and sends a message on a topic. Air conditioner is subscribed to this same topic waiting for a message to turn on or off.

Problem

It's almost all working fine, the problem is that even if the query produces just one result a minute, Lambda function recives it more than once a minute as you can see from the screenshot below:

Problem screenshot

Lambda code is the same of the Kinesis Output Template