For me, it is that very "any" which opens up the second reading. I agree that, RAI, one single ally is probably the correct ruling. But RAW? Hard to say with such screwy wording!
I think RAW is about 90% there. Key is no use of the word of 'each'. There's just the argument otherwise. There's a host of powers that do very, very odd things if you read it otherwise. Including powers that apparently only end if any ally, specific, hits a target 3 times, but as long as no single ally hits more than twice, all good. Look at Deathguide's Sanction or Spirit Ocean to compare...