Add redirect URI for a web application

Yes, you can have multiple redirect URIs. However, they are not in any way related to any client secret/certificate/federated credential, if that's what you are asking (i.e. you cannot use the redirect URI to identify which credential was used, or vice versa).

Yes. A single Microsoft Entra application (single client ID and client secret) can have multiple redirect URIs configured at the same time.

For web applications, additional redirect URIs are added under the app registration’s Authentication settings. The same client secret is then used regardless of which of the configured redirect URIs is used during the OAuth flow. The redirect URI sent in the authorization request must exactly match one of the URIs registered for that app.

The documentation explicitly notes that multiple reply/redirect URLs can be added for a single app registration:

• Web apps can use --reply-urls to add one or more redirect URLs.
• In the portal, additional redirect URIs can be added under Authentication → Redirect URIs.
• A single confidential client app (with one client secret) can have multiple redirect URIs.

References:

• Register a client application using CLI and REST API
• Register a client application in Microsoft Entra ID for Azure Health Data Services
• Register an application with the Microsoft identity platform
• Configure your App Service or Azure Functions app to use Microsoft Entra sign-in
• Set up single sign-on using Microsoft Entra ID for Spring Cloud Gateway and API Portal