Do not require login identifiers attached to OpenIddict sessions to be unique

src/OpenIddict.EntityFramework/Configurations/OpenIddictEntityFrameworkSessionConfiguration.cs

@@ -58,9 +58,6 @@ public sealed class OpenIddictEntityFrameworkSessionConfiguration<
         Property(static session => session.LoginId)
             .HasMaxLength(100);
 
-        // Warning: the index on the LoginId property MUST NOT be declared as
-        // a unique index, as Entity Framework 6.x doesn't support creating indexes
-        // with null-friendly WHERE conditions, unlike Entity Framework Core.
         HasIndex(static session => session.LoginId);
 
         Property(static session => session.Status)

src/OpenIddict.EntityFrameworkCore/Configurations/OpenIddictEntityFrameworkCoreSessionConfiguration.cs

@@ -60,8 +60,7 @@ public sealed class OpenIddictEntityFrameworkCoreSessionConfiguration<
         builder.Property(static session => session.LoginId)
                .HasMaxLength(100);
 
-        builder.HasIndex(static session => session.LoginId)
-               .IsUnique();
+        builder.HasIndex(static session => session.LoginId);
 
         builder.Property(static session => session.Status)
                .HasMaxLength(50);