I just checked; Adobe sell many fonts in the Univers family but none whose name is exactly, and only, Univers. Few of the major font houses sell fonts with a simple name like that. You might see "Std" or "LT" or "BT"; something that is supposed to be unique and overcome the exact problem you have.
At one time this question would have had a simple answer. Adobe invented the first format used widely for quality fonts, and controlled all the fonts. Microsoft and Apple moved to create a rival format anyone could use, and so the creation of fonts exploded and made your question, no matter how reasonable it is, essentially unanswerable. Univers is one of the very well known fonts with countless creators, and imitators, and authorized and unauthorized copies.