[stylist] using multiples in characterizasion

[vejas]

Hi,
In my writing, I often like to use multiples, such as twins, 
triplets, quadruplets etc.
For anyone else who uses multiples in their writing, how do you 
do it? Do you make it so that each is their own individual 
person, even if they're identical? Also, do you be careful about 
the number you use (because I'm interested in really high 
multiples.) Because what I think is, if you had a story about 
identical sextuplets who all like to do the same things, it's 
almost like, what's the point of having all one six if they have 
a similarity?
Vejas