Wouldn't count on anything from petco being het anything. Just because a snake has markings like that on its tail doesn't mean much (at least 3 of mine look just like that and certainly have no pied in them). Was the other listed as a chocolate? The darkness/donut patterns are interesting and could be a sign of it, but I'm still hesitant unless it was labeled as such. Pet stores mostly get their stock from breeder surplus, and I have a hard time thinking a breeder would carelessly let something slip thinking it was just a normal.