2 under 2

Josie • Mommy of a 1 1/2 year old son and due on the 26th with baby boy #2
I just found out we're having baby #2 and baby #1 is 9mnths. I told my sister and she was happy but, she scared me when she said 2 under 2! Any moms out there with advice on how to handle 2 under 2? Is it as troublesome as it sounds? I'm not that worried now but, knowing me, I'll be freaking out later lol