Bootsie & Tootsie
BOOTSIE & TOOTSIE
(both purple with yellow mane and tail, baby blocks on ribbon symbol)
Teeny Tiny Twin Ponies
And if you thought the Teeny Weeny/Tiny Ponies were cute, these just HAVE to be twice as cute. I've never been so fond of the teeny singlets, but the twins are totally adorable in every way. These little identical pairs of twins came out in the USA, Canada, and apparently Australia, but definitely not here in the UK or across Europe as far as I know. The names weren't the most original ever, but Hasbro had devised a way to tell the twins apart via a 'birthmark' kind of system...it is also possible to identify them by the number inscribed on their hoof (either a '1' or a '2' depending on which mould they are in).
In case anyone's desperately keen to know, I think this is how they line up (but this is only on my own deduction, I've not got a pair MIB to prove it!). I think that Bootsie, Sniffles and Rattles are all (1) babies, and Tootsie, Snookums and Tattles are all (2) babies. And as for their tiny birthmarks, well, in general one seems to have it on the face and one on a hoof (as you can actually see in the above picture at least), but I'll let you play with finding out what they are for yourselves ;)
Please note that the ribbons Bootsie and Tootsie are wearing are not original. I think these babies might have come with baby necklaces, but not having one mint in package, it's hard to say for sure. (This is the major disadvantage I have with putting American issue ponies on my page, but I felt it wasn't nice to forbid my US ponies from being photographed, and anyhow, a picture is worth a thousand words ;))

Rattles and Tattles
RATTLES & TATTLES
(both blue with dark pink mane and tail, baby rattle symbol)
Sniffles And Snookums
SNIFFLES & SNOOKUMS
(both pink with white mane and tail, sun baby toy symbols)