Montreal was the only city to issue precancels on the 50 cent (Scott #95) of the 1903-1908 King Edward VII issue.
Two different precancel designs exist, identified in Unitrade Precancel Catalogue as 2-95 and 4-95.
Here is the 2-95 version:

I do not have a 4-95 version, but here is the 4-94 which is the same precancel design as the 4-95 only printed on Scott #94, the 20 cent issue.

You can see the difference in the precancels design; font change, horizontal bars, and the 'Q' of Quebec has different serifs/accent (??).