I agree with some of what both of you said (Cryssoberyl and Yuri Girl 1001) I didn't think they had the best attitudes - I've never liked the whole 'i'll still love you if you go off with someone else' crap - that's the LAST thing you wanna hear off someone who's meant to love you - or how you show your love..
But like yuri girl said I don't think either was thinking of wanting that - they more seemed insecure and worried.
Also, I didn't really get the feeling they hated being not told apart - they were like, it couldn't be helped - she didn't seem really bothered when her mom couldn't tell them apart. I think its common for identical twins up to a certain age to want to be identical in every way including what they do and wear and own - and thats normal - but then at a certain age they want to distinguish themselves and they both become more individual.
And I have heard identical twins often think in terms of 'us' and everyone else - like we think of 'ourselves', and everyone else - it's not unhealthy if you think of that in terms of their 'us' is the same as our 'me' - or fairly close to that anyway.
I'm sure most identical twins go on to become pretty individual - but still think of themselves as an 'us' .
Maybe I'm wrong but I always got the impression unless you WERE an identical twin you couldn't really know what that was like - I mean they are basically the literal other half of you - when a single fertilized egg that should have become just one person, split into two instead of just dividing - their dna is exactly the same, not just appearance.
Like you said Cryssoberyl, to be done really well, you have to handle twin incest more carefully than this - I think it takes more work than setting up a regular yuri couple - (Like my Fav Fanfic - 87k words so far and the twins havn't even kissed yet!) Maybe that's partly the issue - the story is just too short to get any details.
So anyways thanks for your work yuri girl! I'm always up for more twincest and overall I liked it :)