You have to be careful - generally a 12/12 match would indicate a shared paternal ancestor maybe 20 generations ago, or could be a random match,
but the person matching 12/12 may have only taken a 12 marker test, and could be a match at 25, 37 and 67 markers. The same could apply to 25 and 37 marker tests. To be honest, I've never seen the point of taking a 12 marker test, but (as you're finding) most people's knowledge of DNA testing only increases after they have taken a test
It's rather like owning a lottery ticket, but with more numbers on it, and getting prizes with matches you make with others.
You get a small prize for a 12 match, but some people have only 12 numbers on their tickets, and you may have got a bigger prize if they'd had more numbers on their ticket. Obviously, only by owning a ticket with the most numbers on it can you stand a chance of winning the jackpot with a 67/67 match.
With my own DNA test, I did a 25 marker DNA test, with the intention of upgrading to 37 or 67, should a 25 marker match come along. I've had loads of 12/12 matches, but if you live in Europe you will share 12/12 matches with people in most places. No luck on any 25 matches, though.
Your 25 marker matches at no steps means that you share a common male ancestor with these people, and 25 markers at 1 step means that they are a probable match. The fact that they do not share the same name would most probably be explained by illegitimacy somewhere down the line, but that does not mean that they are any less an ancestor, but it does make the genealogy very tricky
