I don't know if this is the right place to send a bugreport. I have installed Flash CS6 126.96.36.1999, but this also happend with my previous CS6. I took some time to find out when it is exactly happening.
I am working in a shared_assets fla file. Here I collect all symbols, assets and fonts that should be exported for runtime sharing. In that file I have a symbol (MovieClip) with some textfields in it. The textfields uses multiple fonts that are marked as 'export for runtime sharing'. In the textfield I use the right fontname (with the asterix). A normal situation I guess.
I want the movieclip to be duplicated. When I duplicate it, the font gets duplicated too. It's named 'HelveticaNeue copy' and is marked as imported for runtime sharing. A side-problem of this is when I just remove the duplicated font, the textfield points to a non-existing font (so when i reopen the file i need to select a font-mapping).
When all textfields are in separate movieclips, the problem does not occur, however its more work in code to reach the textfields.
Hope this can be solved quickly.
EDIT: I just noticed I should report a bug over here, so thats what i did.
I have this exact issue, super frustrating.