Yes, it is legal and I have seen this happen on a few occasions.
The way I always recommended this be handled is to provide the Soldier the opportunity to take the reconstructed packet back to TDS just to ensure the Soldier’s rights are protected. This protects the command and prevents the Soldier from alleging that evidence was in the reconstructed packet that was not in the original packet that was used when he consulted with TDS.
However, if the Soldier reviews the packet and agrees everything is the same, there is nothing wrong with continuing the process with the reconstructed packet. As the servicing paralegal, I would always put a Memorandum For Record (MFR) into the packet that the original packet was lost and the packet was reconstructed.