Strangely enough, I had someone last year with a SA PPL and they came to me for a JAA PPL Conversion before starting an ATPL ground/CPL flight course with a well known provider.
When I pointed out that conversion was not necessary and he shouldn't waste his money, (yes, I do that!), he said he knew it wasn't technically necesasry, but he'd been offered a big discount for starting the course with a JAA PPL - enough to make it worthwhile spending the few hundred to take the 2 ground exams, hire a plane and take a JAA PPL test, and convert.
He passed all the requirements first time, and went away happy and claimed his course discount! (and is doing well I hear).