My 68 roadrunner (project car) has its original fender tag and apparently has the accent stripe option. So I was trying to research this awhile back. Apparently "accent stripes" and "sport stripes" are NOT the same thing. It might be that accent stripes were available in 68, and both accent and sport stripes were available in 69. But don't quote me, I'm a mopar NOOB. My understanding is that accent stripes are thin painted lines applied on the assembly line. Sport stripes may be thicker reflective stickers.
If found this to be helpful from a "sister" site -
Help with pin stripe location
Hopefully the link works - cheers.