Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: If there is data on the target drives, will it a) add to the data (-- I want this!!) or b) erase it?
Document: Bought this for the sole purpose of loading about a gig of data on 500 USB keys. It worked far better than I expected and took way less time.The process is simple: create a &#34;master&#34; that you want to copy; put that in the first USB port. Tell it you're going to copy. Put in two additional keys. Press one button. Wait. For me it was consistently about a minute or so before the two keys were complete. Repeat.
Given the expense of other choices out there, and the fact that this machine doesn't need to be plugged into a computer to work, I have to admit that I was a bit skeptical. In addition, the thumb drives I needed copying were no 512 MB slouches. I needed a full 7.2 GB of data copied onto 8GB drives. At first, like you, I felt I should be able to do this efficiently with my computer. Copying 7.2GB takes 22 minutes on my computer.
You have the option to verify the sectors as well, which doesn't take long and is handy. The master slot is a read-only slot, so you never have to worry about accidentally deleting data.We utilize TrueCrypt for full disk encryption on Linux servers (as a security token in the case of theft), and this device is particularly handy for making quick copies of security tokens. Then again, it works for any application as it's simple sector copy.
So far, I have only used it once, on less than 10 drives, and it worked flawlessly. It was nice to just connect the thumb drives and walk away. After the first run, I knew exactly how long it would take, and could set a timer to come back and run the next set. It copied them quickly and without any errors.
I avoided purchasing one of these for a long time because I couldn't find a simple USB duplicator/tester for under $100. Finally bit the bullet. I'm glad I did. This guy is very quick and intuitive, and it does come with a manual in case you need it. Can copy from the master slot to one or two drives. Very simple - click on Copy and drop a drive into the master slot.
This 1:2 duplicator does just what it's supposed to do. I've duplicated a number of flash drives with it and, from my spot checking and the unit display, no errors have been encountered to this point. This unit does copies MUCH faster than my otherwise powerful laptop. The only reason I left off a star is the manual. It leaves quite a bit to be desired, and there are codes in the display window that I am unable to decipher or find in the manual.
I purchased this duplicator to copy thumb drives that I distribute with pictures and video on them. I occasionally have make these drives (once or twice a year) and usually have to copy less than 50 at a time. Before I used a USB hub and software to make copies, but that did not go so well (failed to copy some of the drives, if one drive was bad - the whole process would stop).
Used this to make 250 copies of a flash drive for a conference. It worked very well and very fast. Much faster than using your PC to transfer files. Indicators tell you if the copy is succesfull. I checked the files on many random samples and all of the duplicates were done correctly. Gave out the duplicated flash drives to the conference attendees and did not have any of them call back to complain. The product works great.
That takes 44 minutes on my computer. Trying other computers resulted in copy times in excess of an hour (my computer is pretty beefy). I purchased this if for no other reason than it would not tie up a machine in my office. Mission successful.It will burn 2 8GB thumb drives in 17 minutes. I'll admit, I was hoping for faster, as that's only 5 minutes faster than the computer, but when you factor in the comparison with TWO drives, it's significant.
I used this device to load 160 USB drives with about 1/2 GB of sales literature and information. At it's best it would duplicate 2 USB drives in a little over 2 minutes. At it's worst it sometimes took a little more than 5 minutes. It wasn't as quick as I had expected, however it was faster than doing the same thing on my computer and it required less effort. I was able to get other things done while it worked. It's also relatively inexpensive.
Answer: B. You are performing a bit for bit transfer from the source to the target USB Key. This device will not add to existing data, it overwrites everything on the target drive(s) in order to duplicate the data from the source drive. It is strongly recommended that you use the exact same make, model and size for all USB keys you want duplicated.