Why do cards like Isochron Scepter have more than one "may" clause?
Warning: Clicking on the first link will download a .doc file.

From A Summary of Recent Rulings published by the Magic Rules Team in February 2005:

ERRATA -- ORACLE WORDING CHANGES

Isochron Scepter and Similar Cards

The Mirrodin(R) block contains a group of cards that create copies of cards and allow a player to play those copies.  The creation of the copy and then the playing of the copy are both optional.  The text has been clarified to indicate that each action is an optional choice.  If the spell can't be legally played, choosing not to use either option is acceptable.  There is no functional change in the way these cards are played.  The new Oracle text for the cards is as follows:
[...]

As spelled out here, the errata was not a functional change, which means that despite how the printed text may be interpreted today, each action has always been optional.

Why would I ever choose option 2? Is there ever a situation where choosing option 2 results in a different game state than if I had chosen option 1?

At the time this answer was written, option 1 and option 2 are identical. However, if a card were printed tomorrow with the text...

Whenever you copy a card, you gain 1 life.

... then suddenly the two options would be different.