So what's the question?

OK, I'll just ask cause I'm confused. Do you mean that you've got peppers on one plant the are purple and others red, without one changing color to the other?

Or do you mean you have purple peppers changing color to red, or red peppers changing color to purple.

Just not clear on what you are asking here. If it is the former, then you have a stem mutation. If the latter, then it is a normal pepper thing.

Never seen a purple pepper that did not turn red when ripe. They even green when cooked.Ive grown Purple Beauties many times Don't leave them in the sun after harvest they burn up fast being purple.

Didn't know that they would turn red,only grew them once before,in a large pot,plant never produced much,then a tree limb fell during storm and smashed it,end of plant so they never made it to ripened stage.