In other words, if a blueprint for a certain module is in a station and I don't obtain it from there, will any other stations in the galaxy carry it? Obviously if this is the case, then I won't have to destroy every hostile station that also happen to be a shop, which would make life much easier.
No, they are not unique.
Blueprints for a given module will show up on several different stations. Most of the more advanced modules will require you to... acquire... multiple copies of their blueprints, but in all cases, there are more copies of the blueprints than you need. So if you need 3 blueprints for a module, there will be 4 or more places you can get it. You can (probably?) always bypass at least one copy of the blueprints for a particular module, so if you're too unpopular, broke, cheap, or poorly-armed to get blueprints from a particular station, don't worry about it; it will crop up somewhere else.