I'll agree. I strongly believe they are bittering it with something other than Citra. This won't have a huge affect on a clone recipe, other allowing you to cut back on the amount of Citra needed.
I highly doubt there's anything other than Citra after the bittering addition. I've heard FFFs talk about how they want to try to phase out Amarillo, so I can't seen them adding Amarillo to the recipe. Not to say Amarillo won't make a tasty beer.
Now for the heart of my rant. Hops of the same variety VARY. A LOT
Over the past year, I've bought Citra from four sources. All four hops smelled different. I could tell they were all similar, and were all Citra, but they were different. Soil conditions, growing conditions, when the farmers trained the bines, when the hops were harvested, the process and temperature of the pelletizer, which way the damn wind was blowing, etc all influence the hop.
This is one thing that homebrewers really don't realize. Commercial brewers choose their hops every year. And I don't mean they choose between varieties. No, they literally choose which cascade they want. Hop Union will give them a chunk of hops cut from the bale (called a brewer's cut) of say, Citra from various farms. They will then choose which they like the best.
Simcoe is a great example because it's only grown by three hop farmers. Brewers will tell you (there's a video out there of Vinnie talking about) that all three are a little bit different. He uses all three, but only uses one for dry hopping, and only uses another early in the boil.
So getting back to my point about Citra. One of the four batches of Citra I got was ridiculously tropical fruit-like. It just absolutely reeked like fruit punch, so much, that it was hard to smell the hop. Another was a nice mix of tropical fruit and citrus, another was a mix of heavy resin and mango, and the final one was mostly resin, and was a little bit catty.
So say I brew 4 batches of Zombie dust using those four different batches of Citra. They are going to taste different. Two or three of them will taste a lot like ZD, but the hop that was resiny and catty probably won't be that close. FFF's probably didn't choose a catty crop of Citra when they got their brewer's cuts. Make sense?
CTZ is probably the best example. Dry hop a beer with crappy CTZ, and you'll know what I'm talking about. CTZ is great when it's 'good'. Dank, resin, a little citrus, and very 'cannabis' like. When it's bad, it's oniony, musty, and almost dirty tasting.
This is one area where homebrewers are still at a bit of a disadvantage when it comes to ingredients. We're often stuck with whatever the LHBS has. Especially with the popular aroma varieties.
rant