The "pointing at the same LDAP" makes me wonder...
Is that the same Zimbra ldap backend (running on one of the two servers?) or do you just mean for the authentication?
Did the accounts get recreated, or just brought back via the existing LDAP? I would imagine they're not going to be accessible via LDAP on the original server since the new server is going to be considered the owning server for the users, so it would point you their if you tried to connect to the old one.
If I've misunderstood that, then the rest of this post won't necessarily make sense for your situation. If I did understand that correctly, then this is what I would do:
Set up an LDAP replica on the other box, let it sync, point the mailboxd on that box at the local LDAP, then disconnect them and promote it to master, so you have two independent Zimbra installations that don't know about each other.
Then use zmprov modifyAccount on the old box to edit the zimbraMailHost attribute on each of the accounts to point them at the local mailboxd on that box. If all of your mysql data is still intact, all of your old accounts should be there and that will link them back in.
Then use imapsync to copy the contents of each of the accounts from the old server to the new one.
Setting up the replica on the new server:
LDAP - Zimbra :: Wiki
Promoting it to master:
Promoting Replica to LDAP Master - Zimbra :: Wiki
Guide to imapsync - Zimbra :: Wiki
I will point out that the imapsync docs there are *way* out of date. Some of the command line options there are useful. Most linux distros include it now so you don't need to build it, just use your package manager to install it. imapsync supports an admin authentication now, so you don't need to screw with any of the alternate authentication stuff suggested there, just use an admin account to log in on each side.
Here's the script I use to restore mail out of local backup restores on the same server:
# Fill these in with your data:
# we write this to a temp file to prevent it from showing up in a 'ps' listing
TEMPDIR=`mktemp -d /opt/zimbra/data/tmp/zmimapsync-$USER-XXXXXXXX`
echo $ADMINPASS > "$TEMPDIR/.password"
# background a thread to wait and delete the tempfile after
# imapsync has had enough time to read it
( sleep 5 && rm -rf $TEMPDIR ) &
--host1 $SRCSERVER --port1 993 --ssl1 --authmech1 plain \
--user1 $SRCUSER --authuser1 $ADMINUSER --passfile1 $TEMPDIR/.password \
--split1 100 \
--host2 $DSTSERVER --port2 993 --ssl2 --authmech2 plain \
--user2 $DSTUSER --authuser2 $ADMINUSER --passfile2 $TEMPDIR/.password \
--split2 100 \
--nofoldersizes --nosyncacls --subscribe --syncinternaldates