Stochastic Consistency Test

Here are 5 jokes:

1. Why don't scientists trust atoms? Because they make up everything.
2. Why did the scarecrow win an award? Because he was outstanding in his field.
3. What do you call a fake noodle? An impasta.
4. Why did the bicycle fall over? Because it was two-tired.
5. I’m reading a book on anti-gravity. It's impossible to put down.

How many are unique? 5.

All five jokes are distinct from one another within this list. However, if you mean unique in the sense of "never told before in history," likely 0 are unique, as these are classic puns.