Yes, you can have more duplicate sensor ID’s reporting to one Handheld. However, if you had 10 sensor units with ID #1 you no longer know which one of the 10 sensor units is in alarm but you will get the alarm messages. Also if using POLL MODE it is quite possible that all 10 units will get the POLL and flash their white LED but the responses from the sensor can collide at the Handheld causing some confusion in POLL Mode.