Here's a place to get locksets similar to the originals, http://www.locksonline.co.uk/a
, catalog/Union_2477_Sliding_Door_Lock.html These sets are a little larger than the originals, but wooden doors can be enlarged to fit. They will take US based credit cards and mail to US addresses.
I didn't think to ask them for a matched set when I bought mine so each has a different key. This isn't a big problem for us since we generally use only the starboard door and the key hangs above it if we lock the door. After I rebuild my doors and put in the new locks I'll just have a different key hanging over the port door.