It's true, only the breeder knows for sure.
But, were they sold to you as standard leucs from Josh's? If so, I wouldn't question it. They look like standard leuc froglets to me. The patterns on froglets are not the same as when they are adults; it will develop more with age.
I'm no "expert", but I do keep 2 morphs of leucomelas, and my breeding group of standards produced over 50 froglets last year.