Hello, This is the first time that I have incubated duck eggs. I have some that are due to hatch on Saturday and those look great! I am a little concerned with what the humidity should be for the last 3 days. The ones that I am most concerned about are some eggs that are on day 12 (today.) Last night I candled and several look like twins. Is this normal that the swimmers look like 2 babies? Basically I am seeing 2 dark spots that look like the eyes and then the lighter area that is tissue. And I am seeing 2 of these. Thanks!!