It's known that some Game & Watch games were produced as promotional versions.
These are games having an additional (company) logo printed on them, on behalf of companies.
It's unknown how many different ones of them exist. But now another one appeared:
Siteco Mickey & Donald
Siteco is a German company with a subsidiary in France that had given away the promotional games.
http://www.siteco.co.uk/en/company/corporate-profile.html
Many thanks to our member gameandwach for the information and the pictures!