They usually add it on as a rider... "now boarding seats 10-24, Gold Circle passengers may board at their leisure". Sometimes they don't say it but they are usually supposed to. If they are being strictly by seat row number they will usually state that and leave out the rider (though I have heard on more than one occasion... "now boarding seats 10-24, strictly by seat row number, Gold Circle passengers may board at their leisure").
As for queuing and RyanAir, unfortunately that does not seem to have been cured by their change to allocated seating. From what I have seen, they still like to get everyone lined up and ready to board. I have not heard of double allocated seats though! That is a good one to watch out for, thanks!