I recently aquired a 3 yo when I had a 9 month old. I was a little trepidatious but I am so glad I did it. They get along well and I don't feel as guilty leaving one alone. It is fun having 2. My second one is housebroken though while my Mayzie is pee pad trained. Mo will use the pad if he is enclosed which is a blessing. Mayzie has even gotten caught up in the excitement of potty time outside and has gone there too! Wahhoooo
I say go for it!