We just got our second dog at the beginning of the summer when Bandit was 2. While it was a big adjustment period (for both us and Bandit) I'm SO glad we did it. I love Nala so much, and it's so great that Bandit has a playmate (even though she still has lots of 6-month old puppy energy and can play for hours on end until she crashes and passes out on your feet).
Go for it!