Yes, the two U's are pronounced differently. The first U is pronounced as "you" and the last is pronounced as in the same way the word "us" is pronounced you-vent-us is how it sounds. Why is this done, I don't know. I am not an English nor am I an Italian major.
I thought they were ALMOST the same but different. (Here we are trying to describe pronunciation with the written word again). I think the second one is more like the sound of u in the word "pudding". In my English dictionary, they try to describe this sound as "uu". That would be yooventuus. But I suppose you should listen to kotzunder instead of me since he's actually Italian.
So I guess I'm half-way between with my You-vent-uus. I guess it's just my own personal thing. Now that you mention it, it is perfectly normal to have an "English" pronunciation and an "Italian" pronunciation. Think of Milan. I canNOT bring myself to call them "MEE-lan", even though I know it's correct. Whenever an English-speaker says "MEE-lan", it just sounds ridiculous. Same with Spanish - "Real THOTHIEDAD", etc etc.