Looks like some fairies have won 2 pots in the advanced quest. Doesn't leave much chance for us, that only cope with doing it once. I guess that's why they get 2, because they have done the quest several times?

Yes, because each entry represents a lottery ticket.

There is no guarantee but each entry increases the chances to win a pot but you still have to be lucky to win one pot or more than one.  It also depends how many people are doing the quest. Usually less people are doing the advanced quest than the easy quest. I have won a pot of the advanced quest previously with one entry, but in the end it is a lottery :-)

All down to luck.  During February, I entered the easy lottery 24 times and didn’t win a limited pot.  During previous months, I’ve won several times with one entry.  It’s just how it works.

Only 62 people received the unlimited pot for the advanced lottery during March, so the odds of winning a limited pot were pretty high. Only 162 entries in total.

The odds are much better for the higher level quests. The only time I was able to do an Advanced Pottery quest, I did it twice and won 2 identical pots. Didn't have such luck with lower levels because many more people do those.

So, instead of spending almost the entire month doing the low level pottery quests multiple times, I now spend more time doing the regular quests and various challenges so I can unlock more animals that are asked in the Advanced quests.

How wonderful for the one who got two limited edition pots! Rejoice in their happiness! It only takes one entry to win.