LDAP Search over 2 BaseDNs

I am using Apache2.0.48 with mod_auth_ldap and am having a problem 
composing a search.  I have a tree with a single Organization containing 
three primary OU's under it.  I want to create an access control file 
which will allow any valid user under either of the first two OU's to 
authenticate, but not the other.  I have tried syntax such as:
  AuthType Basic
  AuthName "Allow Anyone Under Acad.org or Admin.org"

  AuthLDAPUrl ldap://ldapserver.org/ou=admin,o=org?uid?sub
  AuthLDAPUrl ldap://ldapserver.org/ou=acad,o=org?uid?sub

  require valid-user

but it seems that only the last base DN gets searched.

Can I specify multiple baseDN's on one line?  If so, what syntax.

Can I do a baseDN o=wlu search and filter the results for the acad or 
admin ou?
Can someone nudge me in the right direction?

Thanks.

JK