You can only hold one focus at once, unless you have Psicrystal Containment, which allows you to store a second focus. There might be another way to get a second focus too, I haven't read all of the latest DSP stuff.
But note that you could do something like:
1) Expend Focus to use Quicken Power, manifest a Quickened power
2) Move action to regain focus with Psychic Meditation
3) Expend Focus to use Empower Power, manifest an Empowered power
To use your focus twice in a round, despite only holding one at a time.