How to eliminate a packet which will return from receiver(Xbee)?

Currently, I am using XBee Serial 2 for my project. I need to increase its RD data rate up to 60 kbps.
However, it will limited around 32kbps.
I was using a sniffer to analyse packet over the air.
I realized that Xbee will return a packet after it received a packet from sender.
Figure as below, (Third row, Receiver will return a packet), which will spent another 6 ms.

My question is, is there anyway or any firmware version can eliminate this additional packet??

BCS - There is no updated firmware version for the product you are using that would increase the throughput or decrease the RF activity. This activity you are seeing is a result of the ZigBee standard and is not adjustable. If you require a higher throughput without routers to extend the range (Point to point or point to multi-point), then I would recommend looking at the XBee 802.15.4 products instead.

thanks mvut,
What is max. throughput of XBee 802.15.4 ??