Can you seven tools of the bandit a seven tools of the bandit?

Answer 1

Seven Tools of the Bandit is a counter trap, and therefore spell speed 3. If your Royal Decree is set, then you may not activate it in chain because it is only spell speed 2. If Royal Decree is already active though, it will negate Seven Tools when it tries to resolve.

Answer 2

Yes you can. The second Seven Tools of the Bandit will negate the first one, meaning the original Trap Card the first one wanted to negate, will be able to resolve as normal.