I am definitely no authority on the social protocol of that period, but it was my understanding that an individual might only carry ONE card to a social event.
That card was left in a tray, with everyone else's card, at the entrance ( ergo a "calling card").
The total group of cards became a guest register of sorts.
An individual card holder would serve to keep that card unblemished (ie: dogears,, smudges,etc.)

Roger