This has been very frustrating for me to. 

They seem so close in size and at the same time (first born March 2008, second born January 2010) but those few months difference in their birth dates seem to make a TON of difference.

They are not wearing the same sizes during the same seasons AT ALL! 

Having to buy lots of new clothes again which is very frustrating.

My boys are almost 5 yrs apart.  {{5 yrs & 15 months}} 

They were born in different seasons and are totally different body types. My 5 yr old is small, is always true to size or smaller. {{He can still wear 4T)  My 15 mo is wearing 2T already. {{Actually most of the summer}}

I have been able to reuse some clothes but after a few years I found the "hidden stains" have oxidized while stored and don't look too good anymore. 

If I get a good sale I don't mind buying new stuff.  

The seasons do put a kink in the plan. =)

We reused the equipment and some burp cloths. I did trade my boy clothes with my friend who was having a boy. she gave me her boxes of girl clothes. It worked out well.  

My boys are 9 years apart, so automatic no, and my girls are seasonal opposites, so no again.  As they got older, I hoped for some handing down, but my big girl is a jeans and t-shirt girl, the younger is a girly girl, and wants cuteness and dresses.  So, still no handing!  Sigh!  Now I keep a few things and pass the rest on.  Great for my total lack of storage, not so great for the budget.

My kids are all a year to a year and a half apart... and they share clothes, even between genders (if it is not too obvious).  Unfortunately, my youngest won't be getting much as after her siblings have worn them they are pretty grungy!  Like Kessler - I need to go through our clothes stash and purge a bunch too!