A popular audition piece for xylophone, in both orchestral and concert band settings, is "Polka" from The Golden Age ballet by Dmitri Shostakovich. If you are not familiar with the excerpt, please see the notation below which starts at the beginning of the piece and continues through measure 23.
When performing the xylophone part to Shostakovich's "Polka", one might think it best to simply use a single-stroke sticking throughout the excerpt. While this certainly isn't a wrong approach, it's often advantageous on the xylophone to make use of double-strokes (ie. two strokes per hand) — sometimes even triple-stroke stickings (ie. three strokes per hand). Why? The way the percussion keyboard is laid-out, employing double-stroke and triple-stroke stickings can actually make performing the piece easily as well as eliminating mistakes.
One way to quickly realize the benefits of double-strokes is to play scales and/or chord arpeggios up and down the keyboard — shifting chromatically from one to the next scale/chord.
The benefits of multiple stroke types doesn't stop with the xylophone or other mallet percussion instruments such as the bells, marimba and vibraphone. Depending on your drum or percussion set-up, you may find it quite profitable to make use of double-strokes or triple-strokes when moving instrument to instrument, surface to surface, or drum to drum.