Entity Framework 6: Turn off Sequential GUIDs

You can see that the changeset attached to that work item shows that theGuidColumnDefault does not depend on any settings; instead, it just returns the default based on the kind of provider.

It appears from this link that you can manually set it in your migrations, though:

// Excerpt from migration in link above:
public override void Up()
{
    CreateTable(
        "dbo.Items",
        c => new
            {
                Id = c.Guid(nullable: false,
                    identity: true,
                    // You would use newid() instead.
                    defaultValueSql: "newsequentialid()"),
            })
        .PrimaryKey(t => t.Id);      
}