Originally, yes. But very few people use it in that meaning nowadays. It's quite vulgar. I can't remember hearing it in a conversation.
The current meaning became the norm after WWII. It's the standard word for that category of people and is very widely used. The Larousse translation seems to agree with others and with my Harap's. They don't mention "moron". Maybe "moron" is not strong enough? "asshole" may be a good translation, except I believe it is more vulgar: you can't use it in many social environments. "con" is a much more acceptable word, even if it's meaning can be strong. You can use it in just about any social context (if careful about whom it qualifies). Also, unlike something like "idiot", I feel both asshole and con can be used for someone with a normal IQ. It doesn't necessarily mean low IQ or "imbecile", even if it often does.
Maybe there are good forum threads somewhere about that? The precise meaning and usage of such words can be debated endlessly.