Sounds to me like they didn't give you the spokes you needed, and instead cut the corner by giving you all the same...which to me would be unacceptable. I'd take them back and get the right spokes. Having the right length of spokes will make dishing the wheel MUCH easier. Basically just spinning on the nipples will put you right into the ball-park of where you should be, requiring much less adjustment, and not forcing you to move forward in the build not knowing whether or not it's even going to work.
On a related note. I was reading Musson's e-book on wheel building and he writes that original spokes don't have CUT threads, but rather their spokes are forged into shape. This is shown by measuring the outside diameter of the threads compared to the OD of the spoke just before the threads. The forged threads will have a larger diameter than those of 'cut' threads. Which leads me to believe that 'cutting' deeper threads on a spoke machine isn't producing as strong of a spoke as just ordering the right ones in the first place. I'll be building a set shortly (just saving money now and taking the time to build/make the tools suggested in the same e-book) and I can assure you that I'll make sure that I'm getting the proper uncut DT swiss spokes for my build. It's my time, it's the wheelset that I'll be riding for the next 5-10 years at least, and it's just not worth cutting corners.
My $.02
-Jeremy