Chris, I have serial numbers from 52096-52784, and with your number makes a total of 6. They are all from 1896 and are a 5 pin 2 screw lock with the Type I hammer. From what research I have it started in the 52000 serial number range and only seems to be in this range. Serial number 53558 also from 1896 does not have 1896 stamped on it and any above that also made in 1896.
Still a mystery as to why they stamped them this way.