New to bbt charting/ 2nd temp spike?

April • I`m 29 years old (30 in March), my husband is 38, and we have been actively trying to conceive since September 2012.
This is my first month charting my bbt, and I started charting on 02/13 (CD13). It's my understanding that a temperature spike means ovulation, which I'm pretty sure happened on 02/14 (CD14). But this morning I had another temperature spike. What does that mean? Any help is greatly appreciated! Thanks ladies! =)