single sign on using different IdP

[Qian, Yi]

Hello, 

KU has old Shib IdP and recently implemented new Shib IdP 2.3.8 and
migrating SPs to the new IdP, meantime, user complains about single sign
on no longer working, they need to authentication twice because the 2
different IdPs and we have several hundreds SP so it might take some time
to move all the SP to new IdP.

Both old IdP and new IdP against same LDAP server, due to my limited
Shibboleth, I would  like to know is there a way that user only need to
authentication once?

Regards
Yi