I just finished posting something about this last week. You might want to check it out. Essentially the Gossen is a Euro meter and they are balanced for 5500 degree Kelvin whereas the Canon being a Japanese meter is balanced for 3200 degrees Kelvin. The difference works out to exactly 1 stop. I see the same thing between my Gossen and my Pentax spotmeter.

It is my theory that this is percisely why so many people de-rate their asa on most B&W films as they find using the Japanese model the exposures are over by 1 stop. Personally I trust my Gossen and adjust my Pentax to compensate for the error.