"If you breed
motley with no other pattern hets X stripe with no pattern hets ,
you get all motley because motley is dominant to stripe.
Then you take one of those motley offspring and breed it X stripe with no pattern hets
Technically you should get back all motleys, but some may be visually striped, and they should be all motleys. But sometimes there is a gene of motley and a gene of stripe, one of each, and a homozygous motley stripe pops up, but you can only figure this out from test breeding to prove it out."
What Dave means to say is this-
Homo motley X homo motley = all motleys
Homo stripe X homo stripe = all stripes
Homo motley X homo stripe = all het motley AND stripe. Visually these babies will appear motley, but genetically they are het for both genes.
Homo motley X het motley AND stripe = homo motley or het motley AND stripe. Breeding trials will be the only to tell which genes your animal does or does not carry.
Homo stripe X het motley AND stripe = homo stripe and het motley AND stripe
Het motley AND stripe X het motley AND stripe will yield homo stripes and homo motleys and het motley AND stripe. Again, the only way to tell which is homo motley and which is het motley AND stripe will be breeding trials.