Question on English Grammar.?

Question

Having a discussion with a friend we were contemplating the proper use of the following phrases. Which is proper to say:

a pair of twins vs a set of twins. If one uses "pair" does that mean there are 4 individuals total as in 2 sets? One will say a pair of shoes, but is referring only to 2 shoes that match.

and the phrase:

second to last. If there are 15 competitors, if one used this phrase would they be referring to the 13th or 14th place?

Answer 1

I think that pair of twins/set of twins can be used interchangably, with exactly the same meaning, which is there are two people who are twins. If you want to mean there are 4 individuals in two sets you would have to say 2 pairs of twins, or 2 sets of twins.

Of course second to last would be 14th place...I don't see how you got confused.