What if a flight, transporting a recorder from an aviation accident, crashes?
If the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) need to be transported by airfreight, to expedite extraction of the recorded data and analysis of the accident, the probability of the aircraft used to ferry the devices crashing is rather low, as aircraft accidents do not happen as frequently compared to the total of movements per day/week/month/year.

Nevertheless, in the event of the aircraft used to ferry the devices crashing, the FDR and CVR are built to survive crashes and impact, so the probability of the first pair of FDR and CVR being still usable for data extraction after a second crash is quite high. 

Since the FDR and CVR record not only data but also timestamps along with the data, the distinction between the FDR/CVR from the first crash and the FDR/CVR from the second crash is not a problem. Upon data extraction, the investigating party would recognize which flight parameters belong to which flight. Additionally, if the FDR and CVR on both flights were identical models, the serial number of each device would help identification.