It looks like you've made up your mind, but just for the record, I had two puppies at once, from two separate litters, about a month apart in age, and really had no problems with them.
I loved having them together.
It was precious watching them play together, and never really showed any kind of a preference to the other puppy as opposed to us.
The only thing I ever had a problem with was housebreaking but I'm pretty sure it had a lot more to do with the fact that 1. they were small breeds and I find that they're just harder to housebreak period and 2. we puppy pad trained them for like a year, and then tried to switch to regular housebreaking and it was a NIGHTMARE and never worked, we just had to keep them w/ puppy pads because they refused to use the bathroom outside even if you stood outside with them one at a time for like 20-30 minutes.
And we did deal with a little bit of jealousy when they were older, like 2-3 years old, but I don't think it had to do with getting them at the same time or anything, just a problem we had with them.
Anyway, I really enjoyed having two at one time. Large breeds, maybe not so much, but with small breeds I kind of preferred it to getting one at a time. I'm not sure why, I guess just a personal thing. In the (far, far off) future I'd love to adopt a pair of sibling puppies. I'm sure they'll be a pain in the a** (especially because i'm considering large breed siblings) but puppies generally are, anyway.
You can still enjoy them while they're being a pain in the a**.
Or at least I can.