My guess on what has happened...
- "Expert" watches TV...
- Hears the term 'Double Tap" on some movie or TV show in regards to a murder and thought it sounded more dangerous than just a normal shooting, followed by someone having a drinking game later on at the pub with 'double shots'.
- When next interviewed tries to sound like an expert, and add shock factor to the interview, so tries to use the phrase from the movie she recalls, completely misquoting it.
I can see the next expert interview now:
"Yes - the shooter used an astalavista attachment on their aimbot weapon (which can be purchased at any 7/11 store) which turns a semi automatic transmission rifle it into a fully automatic transmission assault rifle - we have to take these guns away from people!"