Everybody has to pass P-Company first if they are to be awarded parachute wings - that includes (well it did in my day) Royal Marines and newly badged SAS if they weren't already para-trained.
Even those with legitimate operational reasons to be para-trained (eg RN SPAG) only wear a light-bulb if they haven't done P-Company.
I would have thought that in these days of tight budgets you would have a hard-time convincing anybody to let you do P-Company and then a four-week static line course just so you can collect another badge. Even then, you might not be allowed to wear it - I knew a lad who was in TA Para through uni, so legitimately earned his para wings, but on joining the RAF he was told he would probably only be allowed to wear a lightbulb as he no longer had an operational reason to be para-trained. That was a few years ago though, so may have changed now.