Psychic levels stacking

[BoomBewm]

Can Psychic levels stack, i.e.: In a Grey Knight Stormraven Wing, the leader can roll to get psychic pilot (level 2), the leader can also be upgraded to fighter ace, and get psychic pilot from that (level 1). Is there anything that prevents a level 3 psychic pilot?

[Captain Bubonicus]

Are we talking about the Fighter Ace rules from Leviathan? If so, I don't think they'd stack - result 5-6 on the Grey Knights table reads:

"The Fighter Ace has the Psychic Pilot (Mastery Level 1) special rule and generates psychic powers from the Daemonology (Sanctic) discipline."

So basically, you'd have two different sources that grant Level 1 mastery.