From what I have read, Marine Traders were built by many companies but imported under the Marine Trader name.
The site above is for US companies only. Heritage East is likely the Taiwanese builder, using Marine Trader moulds to turn out a near copy of the Marine Trader, then being imported into the US together with other near MTs.
There were many builders of near MTs in Taiwan in the 70s and 80s, each trying to get a reputation as a better builder. Some succeeded, others didn't. There is a good article in the TF archives, by Bob Lane, from 1998 Passagemaker Magazine, that sheds some light on the history of the Taiwan building industry.