When you have a domain, access to which is protected by SiteMinder.
Users authenticate via SAML2.0 Federation Partnership.
SiteMinder denies activating new partnership if same remote IDP has been used in another active partnership already.
The following error is displayed in AdminUI:
"Error: Cannot activate 2 partnerships with the same Remote Entity ID!
Please deactivate the other partnership first. "
For SAML 2.0 you need to use distinct Entity ID but you can use the same URLS definition for each entities. It could be a workaround
For WSFED you can use the Disambiguation ID
In the Furture version of the product we will be able to use this functionality. An Enhancement has been opened.