I have a bunch of different syrains right next to eachother. All are true to thier seed
+1 solid advice, it's either that or only grow one variety per season which I've done in the past but can be boring unless you love that one pepper You'd also need to know that none of your close neighbors are growing other varieties as well ...But the seeds from those plants have a very good chance of being cross pollinated and not coming true to type.
Selling that seed as a specific variety is sketchy at best. You have no idea of the genetics of the seeds growing in those pods on your plants.