I look at these 2 frames and somehow they look very similar, almost identical. The geometries are slightly different but the design/shape of the frame, i almost can’t tell any differences. Am i correct?
yes, you are correct sir. do a search on ‘Planet X’ or ‘Karbona time trial’ and you will see the same frame, or a very similar variation, being rebadged and marketed by many smaller companies. As I remember, VeloVie has pretty darn good pricing on theirs, and they even pop up on ebay sometimes with no stickers for around $500.
There was also a lengthy thread on this site on this very subject a few months back…
The Planet-x is the same as many other frames as mentioned above. However, the Kalibur is not one of those… I have a Kalibur and really like the ride, but haven’t ridden a Planet-X so I can’t compare them for you. One non-frame difference is that Kuota would have a traditional dealer network and the support that comes with that, while Planet-X deals directly (or through their US distributor). All reports are that the Planet-X customer service has been pretty good though…
Does the PlanetX have the bigger headtube bearing on the bottom? Also, the Kalibur does now have internal cable routing. But, other than that, it is certainly possible that the factory where PX produces the frame basically “reused existing technology” 
from the Kalibur. Kuota does have an engineering division, which gladens my heart, so it’s possible that they designed the original frame from which all these others are take-offs (but I don’t know that). Does anyone know where the FIRST frame of this ilk came from? Is it the Kalibur, which has been around a while now?
I suspect this may be one reason that Kuota is creating the Kwake. Our very own Paul Thomas is headed to Kuota in Italy later this year, so I’m sure he can give us some info on how they design (and then build, or outsource the build) the bikes.
The fact that the Kalibur won Kona in 2004 would make it a good target for copycats.
other than the double diamond design… i dont see how are the frames similar
if they are, then all bikes are copycats of 1899 (or whenever the first double diamond frame design came out) bike 
Actually, they are NOT similar at all if you look at them in person.
The Kalibur has a HUGE fat headtube of a proprietary size and the Stealth is a narrow funky shape like the QR bikes. Stealth has only a very small section of internal routing near the front derailleur while the Kalibur has more? I think both use replaceable horizontal dropouts. Kalibur uses “Kevlar reinforced” whatever for the rear triangle (presumably to make it stiffer) and has the funky tatoo of Stadler on the seat tube. The Planet X has a picture of a stealth fighter plane on the down tube 
The biggest diff, really, is price with the Planet X much cheaper. Both are fine frames/bikes with some thought on design. Planet X designed the frame and I think 4-5 other “companies” use this mold (LG, Velo Vie, etc.), but I think only Kuota uses theirs because of the proprietary headtube (not very aero though)
Why did Planet-X design the frame and then allow other companies to sell the same frame?
Something about the arrangement with the manufacturer (Taiwan), volume of frames sold vs. price, etc.
And they have exclusive rights to sell them in the UK. Everyone else that sells the same frame is importing them to somewhere else.
A P-X employee posted something about that previously.
Chris