For me it's one big wardrobe mostly. If dt1 wears some jumpers I have to roll the sleeves up he must have shorter arms. Likewise hats I have to roll the front up (iykwim). It must be harder for those whose babies were way apart in growth and maybe have different age sizes. They don't wear identical clothes must just one big jumble of surprises! Though the other day they started off different and ended up the same and I didn't even know I was doing it. I do sometimes (if I'm not rushing and stressed which is rare) look at a top and think 'oh this one will go on dt2 he'll look really cute' .
Mine are ten and some clothes belong to one or the other, the rest get put in a pile outside their bedroom doors for them to sort out themselves! Underwear, school clothes and most pjs are shared between them, just divide the pile in two. They help themselves for the other one's bedroom if they run out.
When they were smaller (under 5) all their clothes were in the same drawers anyway and very few things were specificially for one child. I have friends whose twins know exactly whose clothes are who's and get very upset if they are mixed up or who have a colour code (X wears red or stripes, Y is the other one!).
<waves to wine> I have b/g twins so easier for me but they are different sizes so I keep vests and baby grows separated otherwise would have to faff around reading labels at bedtime. I have a chest of 3 drawers, they have 1 drawer each and 1 for baby grows which has a drawer separator (from amazon, made by oxo). In wardrobe I hang dd clothes on the left and DS on the right, and they each have a box for socks/tights
b/g 1yo twins, one big wardrobe pile. Have just bought a lot of tan/navy/red combos which look equally good on both of them! I quite often get Ds undressed for bed and find that he's wearing a white vest with a pink princess logo on the front (hand-me-downs..). Must put the light on in the mornings!
My girl twins are the same size now and share a wardrobe. Although, some colours look better on twin 1 than on twin 2. We have one gilr who has an olive complexion like me and one who has paler skin like her dad.
My DTDs have their own stuff - they are not the same size so it is necessary to avoid the issues you have identified! I have different drawers in the chest of drawers for each of them or different piles of clothes. Never buy anything the same - similar but different. They have favourite colours which helps and one likes stripes, one likes spots.
So, most of you mix and match, which isn't going to work, as they are different sizes. Time to think along colour or pattern shopping then - except DS2 had DS1's seconds, so were going to have to keep changing who has what!
I have 2 year old B/G twins and one big pile. There are obviously dresses and skirts in the pile, so I try to avoid putting them on my DS
If I were you I'd go for drawer seperators. One draw for vests, split side to side, one drawer for trousers, split side to side etc. if you have two drawers for everything you'll get frustrated when you try to put stuff away!