12-Plate versus 14-Plate?
Hmmm...
What is making it different?
The stem, locknut shaft, trim - grommet/gasket?
From what I can tell...
Aside from the sites graphics I got this from are cheap - the issue of LEFT versus RIGHT aside from being "Mirror images" - ahemn, of each other - the numbers (a.k.a - Part ID) tells the story.
But, this is for USA...
If you're referring to the '12 versus '14 as when it's "born on Date" for Plate - then the year it was made, does not seem to show any differences - so what are you running into?