Closed for Company Meetings: Between September 18 (5pm PDT) and September 22 (12pm PDT), Support and Sales requests will be delayed. Only time-sensitive issues will be addressed during that time. Thanks for your patience.
Not sure whether it is exactly the same or kind of the same. But if a 4 pole filter is capable of filtering at 24db/oct compared to 12 db/oct for a 2 pole filter, then that steepness can be achieved indeed by putting two biquads in series. The cascade~ object is more flexible in this regard. Also take a look at the cascade message to the filtergraph object.