I can see where he is comign from though. As for most "clone" moves, the creators tried to implement a tradeoff of some sorts. Lucas' PK Fire is a godly spam move, Ness' PK Fire does more damage and sets people up for more. Lucas' PK Thunder does more damage, turns tighter and PKT2 covers more distance, Ness' PK Thunder travels faster and has a stronger PKT2. Lucas' PK Freeze is faster and has a freezing effect, Ness' PK Flash is slower and deals a huge load of damage and knockback.
You can see that they tried to balance these moves in some was. If they really are balanced, only time will tell, but there is a tradeoff. As for the PSI Magnet however, Lucas' absorbs more damage, inflicts damage and covers a wider area... Ness' absorbs less damage, inflicts no damage and covers a smaller area (I'm referring to the front part here).
Now, comparing this to the other specials, it really seems strange to give Lucas a move that is superior than Ness' in nearly every way, and it can be seen as unfair.
However, Ademisk, you're 100% right in that it's not that much of a difference and won't have much effect on their charactes as a whole, unless for some reason we find broken uses for Lucas' PSI Magnet, à la Shine =P