Every second month Nina does twice the regular distance, which means 400 * 2 = <<400*2=800>>800 kilometers.
Two years is 24 months, so half of this time is 24 * 0.5 = <<24*0.5=12>>12 months.
So in 12 months Nina does 400 * 12 = <<400*12=4800>>4800 kilometers.
And in the other 12 months, she does 800 * 12 = <<800*12=9600>>9600 kilometers.
So in two years, Nina would be able to make 4800 + 9600 = <<4800+9600=14400>>14400 kilometers.
#### 14400