I only had Kribs for a very short while but the way mines worked out were Females rounded belly and brighter colouration , Male had longer fins and more pointed , but once one of the cichlid folks come along they will put you in the right direction......
It appears to be a male and female. I am undecided about the non-blurry one in the second pic. It's body shape is pointing more towards a female, but the pectoral fins are blue, a sign of a male. Just give them some time.