しばらく沈静化していましたが(^^;)、同じくジャッジリストに、今度はPaul Barclay（MTG-L netrep）からのコメントが出ました。
　これによると、

I think a safer bet would be to say that whenever two or more otherwise
identical cards have some relevant in-game distinction between them, and
that distinction is lost due to some form of random action (the only way
it can be lost), then the next decision about that distinction should be
made randomly with the correct probabilities (if there were two cards,
then there's a 50% chance, if there were 3 cards, a 33% or 66% chance
etc.). Once the distinction is known again, then it is no longer
necessary to perform the random action again. If the cards can be easily
identified (one is signed by the artist, for example), then there will
be no problem. And, please, no jokes about cats during this process.

　ということで、私と同じくランダムで決めるべきだという意見のようです。
（ところで、この "please no jokes about cats during this process"の意味が判る人いますか？(^^;)）