Twins....
Am one and have a matched set of my own.
Lessons learned.
1) Watch the medical bills from the delivery. Every party in attendance for the delivery of my twins had billing errors. I was billed in both of the boys names, Baby Boy, Baby Boy 1 and Baby boy 2. Thats right 5 sets of bills for 2 kids. No kidding, over 7 grand in billing errors. I had to keep a spreadsheet and compare every bill to the explanation of benefits. Yes, two boys and somehow, they billed for 3 circumcisions!!!!
2) No need to buy duplicate toys - it's better that they learn to share.
3) Matching outfits are cute, but not a good idea once become mobile. It's a lot easier to know you have seen both, rather than the same kid twice if they are dressed differently.
4) Identical - figure out some way to KNOW which one is which, especially as infants. The first year is a very sleep deprived experience and you don't want to double medicate one and not treat the other.