Hello John G,
I am sorry to be pedantic about this, the type approval is a legal documentcan and only be issued to the submitting manufacturer. With gas appliances, the approval not only covers the design, but the specified methods of manufacture and testing, deviations from these automatically requre additional approval. I do not know, but perhapse tow hitches also have such stringent approval procedures.
'Type approval' (as the process name suggests) requires that a sample of the product to manufacturing specifications with all instructions and documentation is submitted for testing, and either passes or fails the approval process.
As the copy was not manufactured under the same production regime with the same control of raw materials, production techniques and testing as the original, the copy cannot claim cover from the original type approval. In fact any such claim would be fraudulent.
I also suspect that if the original manufacture were aware of a copy being marketed and claiming type approval, there would be legal action against the copier.
Just as a matter of detail, the materials used in the copy may appear to be identical, but what if the wrong type of steel/casting has been used, what if the case hardening/chroming has not achived the required thickness etc. to all intents and purposes the copy appears to identical but may not be as durable, or amy not have the required deformation charateristics under abnormal conditions.
Of course the copier could submit thier vesion for type approval.