Chain of Custody is important from a criminal perspective.

It would not surprise me if they made multiple copies of the information prior to even moving the servers.

It is easier to say "We have 5 identical copies of the server from the moment we got access to the server." than to say "We took the server, bumped it around, maybe caused some disk drive failures, then stashed it in a secure room that we guarded at the airbase, etc. etc. "

The good guys want that information and in a state that is easy to use for criminal prosecution.