If looked through the rule book and the errata and I can't find any thing on this so I hope you can help.

When have the option of placing recharge token on more than one card can you choose a card that is not already in use?

Example 1:

Player gets an hour glass on his roll, the GM picks one of his unused actions card and puts two recharge tokens on it.

Example 2:

Player uses reckless cleave and chooses to put the recharge token on an unused active defense.

LoveSkylark said:

Yes, any action, even one not recharging.

If you have the Player's Guide there is an example on page 84 where the GM places two recharge tokens on the player's dodge action, despite it being the first action of the combat.

EDIT:

Sorry to contradict my own reply but your Example 2 is (possibly) incorrect, if you have the choice of putting recharge on a card yourself (e.g. through a card effect and not a delay symbol rolled) then you the action you place it on must be one you could use, e.g. you could not place it on block if you had no shield; otherwise what I wrote first stands, any card, even one not recharging.

A minor point in related to your question; in the case of the delay, it's up to the GM to assign the tokens and when using reckless cleave the player picks which one to put the counters on.

So the only real rule on where you can place the recharge token is on an action that the target is able to play at the moment the effect happens.