UPDATE:
Seems this is due to a bug in part of the Real-numbers readout system and not the power itself.
A character with their real Numbers tab open can verify that any allied buff cast upon them (powerboosted or otherwise) DOES actually overwrite the values of an older buff with those of the newer one. However, the numbers listed for buffs in the team or pet windows WILL NOT CHANGE when those buffs are overwritten.
This display bug makes it a bit harder for a buffer to rememeber which allies they've Powerboosted and which you haven't, but at least they're actually all getting the proper buff values.
Does this bug also apply to the purple pet set?
I thought my Photon Seekers where a bit weak in the damage department when I dusted off my PB the other day.
I really should do something about this signature.
Sure this is the right thread Praf? 
If that was about the Recharge Intensive Pet Enhancements, were you exemplared at the time?
There's a seperate issue relating to any Damage Enhancement granted by Purple Sets in Photon Seekers vanishing when exemplared. Any enhanced damage granted by Purple Sets is only getting applied at level 50, so if you exemplar at all (even to level 45 via Ouroboros) your Seekers will only deal base damage.
I'm trying to get word on both issues. Have submitted bug reports in-game without any luck and the Reps/Devs inboxes are full... tried the PlayNC website earlier today and the query has been elevated to a Senior GM.
Arg, wrong thread!
And yes, I was exemplared.
I really should do something about this signature.
Something rather weird is happening with Power Boost.
Lets see if I can explain this without nerfherding any particular powersets...
1. An allied buff grants an effect at 100% strength.
2. Power Boost increases this by 120% strength.
3. If Power Boost is used before the buff is applied, the effect kicks in at 220% strength (100% +120%).
All well and good so far... now here comes the funny bit.
If the buff is re-applied normally (without powerboost) before the duration of the Powerboosted buff expires, you would expect a fresh application of the buff to be applied at 100% strength.
However, this is not the case... at least according to the in-game "real numbers" readout.
>>> On reapplication of the (100%) buff, the duration of THE POWERBOOSTED BUFF (220%) is reset <<<
In other words, to get permanently powerboosted numbers for an overlappable buff, you need only actually Power Boost it once and then reapply it normally before the first buff wears off. Given that Power Boost only lasts a short time (compared to the duration + cast time of certain allied buffs) this seems rather exploitable...
I've used power boost effects before, but not with overlappable allied buffs. Is this normal behaviour? Or just a strange quirk of the 'real numbers' display? I'm guessing the latter, but wanted to check...
Note that the same thing is also appearing to happen in reverse: If a Powerboosted buff (220%) is applied on top of an existing normal-strength buff (100%), the duration of the normal-strength buff is reset - the buff stays at 100% strength instead of being overwritten with the stronger 220% version...