I always use Break Free. As far as the Suffix- it is all stamped. Not sure what you mean by a "duplicate serial number". The two x's I put in the number are just so I don't put the serial number up for the world to see, if it makes a difference or not. All the numbers appear to have been stamped at the same time including the last A. Is this a bad thing? Too bad about the box. It has an unopened tool kit with everything in it and all the correct paperwork down to the warranty card. The paperwork shows the 7 3/8 with the break. I feel like trying to contact the original owner who is an older gentleman in the area and find out if he may be able to dig the original box up or find out what the story is.