What are the chances of that?

As some of you may know, Matt has two siblings. A 35 year old brother named Sean and a 34 year old sister named Sally. Both are married with no kids, but over the summer, they talked to each other and decided it was probably time to 'start trying'. So Matt and I made bets on who would have a kid first and what gender (Matt: Sean with a girl Whitney: Sally with a girl)
Saturday afternoon Matt and I were about to start a hike and he gets a call from Sean. The usual brotherly love (EX: What's up fool? Not much sucka) was exchanged and then I hear Matt say "Really? That's awesome!".... Sean (well, his wife Fiona) is pregnant and due May 13th!!! Wahoo!
So Sunday we are down at Matt's parents for a hike and some dinner and we are all talking about the upcoming baby and the fact that no one can get a hold of Sally to tell her about Sean. Sally then calls.... I answer the phone to be a smart ass and we talk for a minute before she says "I have some news, but I guess I should tell my mom first." That's right folks, SALLY is pregnant as well and is due MAY 14th. ONE FREAKING DAY AFTER SEAN'S BABY! Is that possible?
We spent the rest of the day saying "Two Babies!?!?!" and Matt and I have been talking smack over the bets... it could turn out to be a very close race! (ok, that is a horrible way to put it, but we only bet doing laundry for who comes first, as for gender it's bathroom/toilet cleaning)
My mind is boggled by the fact that these two couples happened to get pregnant so quickly and close together! I can't even imagine how funny the phone converstation between them was... all four of them on the phone "we're pregnant" "no, we're pregnant".... awesome.
So, CONGRATULATIONS to the soon to be parents! Enjoy being pregnant and I hope you have happy, healthy babies!