Does your pal number change on an upgrade? (I don't think it does but I'm sure someone can confirm)
Your actual number doesn't change, they just add a "0002" to show that it's the 2nd issue. Funnily I have my very first PAL/RPAL but have a 0002 after my number because the card they issued first they sent to the wrong address, so they had to issue me a 2nd card..their screw up not mine.