I'm looking over the crafting rules (and specifically, golem types) in preparation for playing in a new campaign which I'm told will have plenty of "downtime," and I've noticed something which seems to me to be a bit of an anomaly.
Assuming that character X wants to construct a golem themselves, from start to finish, that means that X must pass the mundane skill checks required to create the golem's nonmagical body before even getting to spellcraft and all the rest. In all cases I've seen but one (and to the best of my memory, this extends to other fields of crafting as well), there is either a single mundane crafting skill listed, or a choice between A or B. See the Clockwork Golem for one example. "Craft (clocks) OR craft (locks) DC 20"
The Cannon Golem, however, reads: "Craft (siege engine) AND Knowledge (engineering) DC 25." Is this intentional? Is X required to spend the time and resources necessary to succeed on two independent DC 25 crafting checks to construct one inanimate body? Is this unique, or are there other items which require multiple mundane crafting checks to construct in the RAW? Or is this a typo/has it been errata'd, etc?