Thanks @Chingford, I am not unhappy just concerned it may lead to corrosion etc but if they are inert then I am fine. I believe he has sold them all now but this is an upgrade.
I think it is a case of one (or both) being off-centre. Need a larger statistically significant sample size to confirm.
The gap from the crown to the letter looks to be the same and the rim on one is not cleanly struck.