Yes.

I fly or have flown HiTec and Hobbico servos on numerous airplanes, and after hearing the same thing, did a bit of "home testing" if you will. In SOME cases, they're the same servos. Take a look, for example, at a Hobbico CS-73 Giant Scale and an HS-755HB. You'll note, for example, that HiTec's listed dimensions are merely the Hobbico dimensions rounded to the nearest .1 inch, and the torque is identical. If you pull them apart (I have) you'll see the "composite" gear train of the Hobbico is the "Karbonite" gear train of the Hi Tec. You'll also find harnesses of exactly the same wire, and even identical "miscellaneous fluff" such as the rubber grommet for the harness or the case screws.

Safe to say that if you find a Hobbico servo with a HiTec "equivalent"...that it to say, 2 servos with the same dimensions and similar or identical performance numbers, they're likely the same critter on the inside. Now, clearly, each company offers servos the other has no "match" for, so my GUESS is that it's not so much a case of one plant makes both, and slaps different labels on as it is a case of both companies purchase raw components (gears, motors, cases, etc) from the same folks. That is, however, just a guess as I say.