Strange nisMapEntry

Hi all, I have in my ldifs, whatever the way I do them (slapcat ldapsearch -LLL...) some strange entry, like if it was hashed.

Here is a sample: nisMapEntry:: LXJ3LHRjcCxpbnRyLHJzaXplPTMyNzY4LHdzaXplPTMyNzY4LHRpbWVvPTUwLHJldHJhbnM9MTAgeWFrMjA6L3VzcjIvdXNlcnMvJiA= Which should be: nisMapEntry: -rw,tcp,intr,rsize=32768,wsize=32768,timeo=50,retrans=10 yak20:/usr2/users/&

If I re import them from a fresh "normal" ldif generated from my nis automount maps, it does the same, it's alway the same affected entries... In phpldapadmin I can see it well, but not in my ldifs and its a bit annoying for me... Any idea ? Thanks,