Everything seems to be in order.
Server has to send acknowledgment to a device when it tries to establish a link and send an AVL data. So if you are receiving that data it means acknowledgement is reaching the device.
As for data itself it is not same AVL data, timestamps are different and Io ID 66 which is external voltage varies from record to record. Records are sent at frequent intervals, so it could mean that not much changes every ~30 seconds record is created and that your device is stationary.
If you have anymore questions please ask.