Thanks for the suggestions, Lorredan and SteveM.
Lorredan wrote
I was very fortunate to see a 15th century clothing exhibition in Milan. I also learned that the Calze of red and white were the Ghibillene colours, and also the the colours of the crest of Pavia and Cremona; which was a Ghibillene stronghold. The Ghibillhenes who fled Milan were restored to their positions when Francesco Sforza became Duke.
http://en.wikipedia.org/wiki/Pavia
Guelphs for the Pope and Ghibillenes for the Emperor (especially Frederick)
~Lorredan
Red and white were also the Guelph colors. In Lombardy, Ghibelline Pavia had a white cross on a red backgound, while Guelph Milan had a red cross on a white background (see pictures at end of
http://en.wikipedia.org/wiki/Guelphs_and_Ghibellines). In Florence, it was the same with a lily.
The association with Pavia is promising, however, as the Sforza had a tradition in which the eldest son had the title of Count of Pavia, as you can verify with a Google search of "Count of Pavia"--Galeazzo Maria had that title, and then his son Gian Galeazzo. Before that, it was the Duke of Milan who was Count of Pavia, starting with Gian Galeazzo, as far as I can tell from Google. so Galeazzo Maria's hose may well relate to the title of Count of Pavia, even though the color might not be quite right (Pavia's color isn't dark red).
Steve: on Google I cannot find any identification of the mulberry tree with the dukes of Milan before Ludovico, and with the Duchy of Milan before the "late 15th century". [Added next day:] But now I see from your post in the "Woodblocks" thread that Filippo was the one who got the industry going, starting in 1442, a policy expanded by Francesco and Galeazzo Maria and continued by Ludovico. So it is possible.
[Please ignore what I wrote initially, i.e.: "I also find "after 1450", which might include Galeazzo Maria but not Filippo, who died in 1447. And I can't imagine that if the calze colors were Galeazzo Maria's property, they would also have been worn by Ludovico, at least while Galeazzo Maria was alive and probably also Gian Galeazzo."]
If the hose on the CY Lover card is an ordinary red (with the other leg white), it may indicate Pavia, and hence any of Filippo Visconti, Francesco Sforza (if the card was made before the title of Count of Pavia was given to Galeazzo Maria), or Galeazzo Maria Sforza. If so, the hose heraldic is not very helpful in identifying who is on the card. {Added next day:} The same would be true if the red hose is mulberry-red.
Then the puzzle is, who is the man on the PMB Love card, who has two red hose? Maybe that was Francesco, taking the red of Milan and ignoring the white background and its Guelph history. Or maybe hose color wasn't important at that particular moment.