What I do is:
1) Took an slapcat generated LDIF from a 2.3.x setup
2) Removed all entryCSN and contextCSN lines.
3) Ran "slapadd -S 1 -q -w -l ~/load_noCSN.ldif" on server-1
4) Did a "slapcat > toserver2.ldif" on server-1
5) Started server-1 and let applications create and modify objects.
6) Moved toserver2.ldif to server-2.
7) Ran slapadd -q -l toserver2.ldif on server-2
8) Started server-2
Now - I would expect the objects created on step 5 to appear after a
while on server-2. They are not.
However, objects created on server-1 after both servers has been started
are replicated.