The poorly named Unique Assets can be obtained in multiples, and some, such as the Old Journal and the Dog Sled, can be acquired in multiples. The FAQ is clear on this.
Can you use multiple actions on identically-named components in a single round? Can my two actions for the turn be to read my two Old Journals? And if I can, does this mean that two Dog Sleds go twice as fast as one?
Being able to read multiple books seems intuitive, but being able to ride two sleds at once does not, so I'm not certain how to rule. The base game is clear that you can only use each action once, but no distinction is made between only getting to use one action per distinct component, or one action per uniquely named components, because before now it was impossible to get two copies of the same card. Could you get out of Debt twice if it was possible to have 2? Could you cast two separate spells that had the same name, if that was possible? I don't know.