Responses to broadcast messages XBee Pro 802.15.4

I am trying to test the broadcast messages and receiving responses from other nodes that receive them.

Here is the test case:
I have three end points. I am sending a broadcast message with content “test” using TX64 req to other two nodes from the third one. I need both of them to respond again with “test” string. Responses are TX16 messages directly to 16bit address of the third (broadcast originator) device. When only one of them is active everything is fine. However, when both of them are active the “0x01 - An expected MAC acknowledgement never occurred” status is received within the TX Status message. Sometimes I receive both responses, but most of the time one or both of the responses never arrive to the broadcast originator.

What would be the problem and the solution?

There seems to be a sort of collision or a similar issue. However I do not want to take any precautions without understanding the situation fully.

Many thanks for your help in advance.

Are you trying to set more than one radio to the same 16 bit address?

Yes, I want to send the data from more than one nodes to the same 16 bit address. I have set the RN parameter of the devices so the problem was solved but how could I solve this problem without changing the RN parameter? Is it possible?