Thanks guys, I did not know I can put another -k options. so my code looks like
sort -k1n -k3 names
62 martin adrov
62 jan nedorost
154 michael cores
154 alfonz novak
I tried that with one -k options and comma separate columns (according to man page that way I understood syntax).
Just for curiosity what is difference between "-k1n,3" and "-k1n -k3" teoreticaly both should do the same thing but practice is different