You're all beating around the bush I'd say.
Which is the actor, already identified here as one of the 15 characters, who also played another one and a half?
So, who, where and why?
It seems to me that it means: which one of the 15 "actors " whose picture appears in the puzzle played another "one and a half" of the characters that 'you've identified. Why go looking for James Bond, Maciste or any ambassador in Mexico? The list is simply: Philip Marlowe, PapaThorson, Lemmy Caution, Nick Charles, Dr. Mabuse, The Saint, Don Camillo, Mike Hammer, Batman, The Falcon and OSS 117. That's it.
Carnut found out that both Conway and Sanders had played The Falcon
and The Saint. If he is right it must be one of them.
The question is not auto related.
Of course you may want to try and understand what I mean by "a half". You haven't yet.