right, the 18th scale motors are the same motors that Castle use.
The ESC's are totaly different, I am assuming that you don't have much knowledge of the electronics industry, but at times, although you design and prototype in-house, but it may be cheaper to have it 'manufactured' outside, this doesn't mean that the unit isn't Tekin designed, just it has been put through a solder bath in a faceless manufacturing plant to keep costs down.
Now, if this HAS happened, and there is a remote possibility that Castle do it to, then very VERY remotely, they could be done in the same place.... but they would be made to Castle designs for their ESC and Tekins design for theirs.