I've ordered from McMurray three times. First order they sent along an extra couple of what I had ordered, plus an Easter Egger rooster.
On the second order I ordered Rhode Island Red pullets, Buff Orpington pullets, and Barred Rock pullets. They didn't send the Barred Rocks, but sent an extra RIR pullet. They also sent 5 extra yellow chicks (as an apology for not having the Barred Rocks I suspect), which I as a newbie thought were Buff Orpingtons for the longest time, but several months later learned they were Buff Minorcas (at least they were pullets!). They also sent along a Blue Cochin which didn't ship well and died that evening (the rest of the chicks did fine).
Third order they sent along an extra couple of what I ordered, plus a White Crested Black Polish rooster.
I also ordered from Ideal earlier this year and they sent me exactly what I ordered, no more, no less.
All of the chicks I've ordered from both hatcheries have been sexed 100% accurately (100+ chicks from McMurray and 20+ chicks from Ideal).