Riddle of the two portraits.
 

Levitsky, DG Portrait of Grand Duke Alexander Pavlovich in childhood ( TG) . 1787. Oil on canvas , 60.5 x 50
In the portrait depicts the eldest son of Emperor Paul I and his wife Maria Feodorovna , the grandson of Catherine II, the future Emperor Alexander I (1777-1825). As befits a member of the royal family, to Alexandra ribbon of the Order of St. Andrew and the Order of St. Alexander Nevsky.
 
In one of the directories CHRISTIE'S /2008, found another portrait of Alexander vel.knyazya . Written , as mentioned, on or after portrait DG Levitsky. CHRISTIE'S|NEW YORK. RUSSIAN ART. 18 APRIL 2008. LOT № 7
After Dmitrii Grigorievich Levitskii ( by DG Levitsky ) Portrait of Emperor Alexander I of Russia (1777-1825), oil on canvas. 24 ¼ x 19 ½ in. (61.6 x 49.6 cm.) Almost the same size.
Frankly, I just second portrait appeared earlier than the portrait Levitsky 1787. Who , after whom?
Interested in your opinion .

And here's another "after Levitsky" (Levy y cue) ...
"Portrait Of Grand Duke Alexander Pavlovich, The Future Alexander I", oil on Canvas ....

If I'm not mistaken, according to the accepted terminology, the leading auction houses , such a statement can only mean :
"The name of the artist preceded by" after ": In our opinion this is a copy of the work of the artist".
Ie in no case does not mean "after," it means " copy from the author's work ," or, in extreme cases, based on the author's work ...
A copy of wear out too ... Masters mass .