As someone that ran one of these small computer repair shops for several years.

Yes it's common practice to make a copy of the drive.

First thing we would do before even booting to the hard drive was to make a copy. That way if any data was lost or destroyed during the repair we still had a copy and could possibly recover what was lost.

Yes, we do find stuff that people wouldn't want to be known. Sometimes its accidentally that we find it, sometimes its right out in the open. usually it isn't looked at in detail, but if someone didn't return the call and you thought it might be something important you might look farther.

Found some child porn once on a clients computer, talked to our lawyer and he said that once we found it we were obligated to report it. We did and found out that there was already an investigation into the guy. There was already a search warrant issued but they had been unable to locate the computer. The client had suspected a search was coming and had brought it in for repairs to hid it from the cops.

It was a similar story, computer was dropped off for repairs, repairs were made and we couldn't get in contact with the client. After about 3-4 weeks an employee looked it over to see if we could find any more contact information, that is when the child porn was found.

We reported to the local sheriff, and a day or two later the FBI showed up to collect the computer. We never told them about the HDD clone and just deleted it, unlike the guy in Hunters case. I didn't want any chance of anyone finding the same stuff on our backup drives.