I find it ludicrous to think that a collector of Fine Art, or any art for that matter, could be taken in by any artist`s claim that many buyers pass off their copies of well known masterpieces as originals. Surely, even if there are the occasional duplications of a well known paintings, such as Le Dejeuner sur l`herbe by Manet and The Card Players by Cezanne, most art lovers would not be taken in by claims of originality when the original is either in a private collection or belongs to a city or country`s art collection.
Of course a forgery can be made in the manner of another artist and this has probably been tried a lot, but it is illegal to try and pass of a forgery as an original and gaol could be the outcome on being found out.
So by all means make a painting after the style of an artist you admire, but be sure to sign it in your own name and include the phrases `After whoever` in the case of a copy.
To finish, it is difficult to see how an artist can describe something as `an original copy` unless he or she knows for certain there are no other copies in existence. For example, I have completed a copy of a Rembrandt portrait of an officer, of which I know there is at least one other copy in existence and that is in the Rijksmuseum in Amsterdam, therefore my copy cannot be an`original copy`