I'm sure my dc both dropped 2 naps well before they were 2. I remember panicking that they would wake up early if they went to bed very early but they didn't, even if they went to bed as early as 630pm!?
2 naps just isn't practical sometimes, especially when you have other children. My ds dropped his naps altogether when he was only just 2, largely due to dd not going for a nap. DD, on the other hand still napped in the afternoon when she was 4!?