[alsa-devel] audio mixing

I am using alsa libs to mix audio alerts in my application. I am using the aplay code as an example. I am playing two audio files, one that is 5sec and one that is a beep, from two different threads. The thread that plays the beep loops and plays it every second. I am playing the two audio files through the same snd_pcm_t handle. When the 5sec audio file finishes I then the pcm gets into an xrun state. Instead of using the same handle for all audio should I just associate one handle per audio file? Is there something else I can do to make the pcm handle more stable when playing multiple audio files?