Choosing an inductor for a synchronised interleaved buck converter
What does that that mean?


Inductance can be defined as an amount of flux developed per ampere (you can calculate by yourself from \$V_L=L \cdot di/dt = N \cdot d \Phi /dt\$). So, it is easy to think that if current increases then so does the flux. But there is a point that the flux cannot increase more. This is called saturation (remember B-H loop) it causes inductance to drop which can lead a rapid increase in current. 

Now you might think that "Hmm, for proper operation, inductor current should be lower than saturation current". This is generally true but depends on the application. According to the datasheet you provided, for 0.66ADC, inductance drops %10. This can be acceptable for your application because your DC current is lower than saturation current. 

By the way, 15kHz switching frequency seems low to me. 40-50kHz would be nice though. So you can select a smaller inductor with higher saturation current.

Interleaved converter approach is quite unnecessary for your application but if you go for it then yeah, current can be halved for both but results in increased cost and size. Increasing the frequency to 40-50kHz is a better option.