Phrase two - two expressions I found myself wondering about

There are phrases that we often use in everyday language without giving a 2nd thought.
Sometimes I'll find myself wondering 'where the hell did that expression come from'. Two that I've pondered recently are 'dead ringer' and 'scot-free'.
Dead Ringer
Contrary to what some may believe, this expression has nothing to do with ringing a bell from within a coffin.
Apparently in horseracing circles a 'ringer' is a horse that's similar in appearance to another one and is used as a substitute (dishonestly) in races. This is done to defraud the bookies. So the word 'ringer' has come to mean any very close duplicate.
Dead, in the sense of lifeless, is so commonly used that we tend to ignore its other meanings. But 'dead' also means exact or precise. E.g. 'dead shot', 'dead centre', 'dead heat', etc.
So combinge 'dead' and 'ringer' and you get something that means and exact or precise copy.
Scot-free
My initial thoughts were that this had to have somethinng to do with a Scotsman who got away without paying for something. Others seem to think that it had something to do with a slave called Dred Scott who was made free by his owner. Neither is the correct origin.
Scot is a Scandinavian word for tax or payment. It came to the UK as a form of redistributive taxation which was levied as early the 13th century as a form of municipal poor relief. The term is a contraction of 'scot and lot'. Scot was the tax and lot, or allotment, was the share given to the poor.
Scot as a term for tax has been used since then to mean many different types of tax. Whatever the tax, the phrase 'scot free' just refers to not paying one's taxes.
Now that makes me wonder why scotland is called Scotland . . .

