How to avoid multiple copies of answer against a query from end device while using a repeater

I am working on a WSN set-up. I posted a question earlier on the same. I had a another question with respect to the same. My question is while working in broadcast mode, if Coordinator and end device are too far away and we are using a repeater in between , then its fine, repeater will only braodcast message to End device and End device will not receive multiple copies of queries (as it happen in a case when Coordinator and End devices are in Range and we are also using a repater, although in this case there is no need of using repeater). Now assuming that end device receive multiple copies of queries, how we can neglect other multiple copies?

I am attaching a pic along with this question.

Should i use time stamp? I really don’t have any idea regarding how to use time stamp to avoid using multiple copies? Probably i should add time stamp in the querry send by the coordinator(Running on Raspeberry pi, equipped with OLP865 Xbee). What if i don’t have internet access on Raspberry pi and no RTC. Probably i should use a series of number(generated from a software). On the End device side(Running on Arduino), i should, parse the incoming string, store that time stamp/number and match it with the next incoming query, if they both match, drop this next message, if not, process the query. Can any one verify, if these seems to be a right approach or if there is any other method?

For original question, kindly have a look at this link

If the end device or the coordinator receive duplicated packets that are sent from the same node, the XBee modules will automatically filter them out and only let one copy of the message through the UART.

I am using a repeater in between the coordinator(master) and end device(slave) and that is why i am getting the duplicate packets. And yes i am getting duplicate packets from the end node too, as end node is getting 2 queries i.e one from the master and one from repater(they all are in close vicinity of each other, as i was doing some inhouse testing).

What is the DL and DH set to on both the Coordinator and end device?

I had tried configuring them like this
Master Slave

Then the only way you could be receiving duplicate packets is by your application sending more than one packet out the UART.