Listening on multiple ports for openldap 2.3.33

["Douglas B. Jones" <douglas@gpc.edu>]

I want to listen on multiple ports for openldap. Not ldaps, just ldap.
I have tried (let's say port 100 and 200 - not the real ports):

ldap.conf:

URI     ldap://0.0.0.0:100 ldap://0.0.0.0:200

and

slapd -h ldap://:100/ -h ldap://:200/

It always only comes up on port 100, never sees port 200. If
I swap the numbers, then port 200 comes up and not 100. I am
not sure what I am missing. Thanks for any help!