Hi Michelle.
My DS is 13mo (nearly 14mo) and only has one sleep through the day. This is normally just after lunch and he sleeps anywhere between 1/2 hour to 1 hour. This has been the go since he was 1yo. Occasionly he will have another nap at 4pm however when he does, we know he wont be going to bed at 8pm. (normally about 9pm).

Although he is a pretty good sleeper at night. 8pm - 7am (sometime 9am)

Mick