They look similar but certainly not identical from the photographs at least, and even the article later mentions, "he looked startlingly like the first one." (not identical).
"The William and Will West story is somewhat sensationalized and omits prison record information, uncovered by later researchers, indicating that William and Will West both corresponded with the same family members and thus were probably related.
Prison records also cite that Leavenworth inmate George Bean reported that he knew William and Will West in their home territory before prison and that they were twin brothers."
