If you actually read the quotes in articles, the SNP have been very clear, but the headlines have mostly been twisted out of all proportion with the facts. Such is the current standard of Scottish journalism.I don't know about that. Most of my friends (ages 20-24) who voted Yes because of nationalism/fuck Westminster etc seem to want to Vote Leave because "why should we be part of the UK and the EU I want Independence!". Yes they are wrong and misinformed but how widespread is this feeling? IMO the SNP haven't done a good job in explaining this to their supporters - being an Independent country within the common market.
In fairness, there must be a fair number of 'Yes' voters that will have been happy with the threatened idea that leaving the UK would mean getting kicked out of the EU, so it's not a big surprise there is overlap with 'Leave.'