the description of an event says "One of the special event cards":
1)is it a random card?
2)is it a random UNOWNED only card?

in other words : if i won SE in, say, honey pot, will i be able to win another SE in honey pot, is the situation possible when i already own prized SE, so i will actually win nothing?

the description of an event says "One of the special event cards":
1)is it a random card?

Yes in the Event, if you win an SEC it is a Random SEC card.

2)is it a random UNOWNED only card?

Correct, it is a Random SEC card only from the ones you do not own.

when i already own prized SE, so i will actually win nothing?

If you already Own ALL of the SEC cards, then the SEC can not be won as a prize.


The Progress bar.
Filling up the Progress bar for the 1st Time, Wins a Specific SEC card.
If you own all of the SEC cards Already, then the 1st fill of the Progress bar is for a Joker card.