I've only done this once...and there's a reason for that!! It is very hard work indeed - there were 6mths age difference between my two (a Rottie and a GSD).

Yes, the advantages are that the two of them play together,tire each other out and are company for one another. But, they can also set each other off being naughty ie: if one decides to bomb off after another dog the other will surely follow!! Keeping an eye on two dogs is much harder than one lol

Training takes twice as long - I had to set extra time aside to train each one on a one-to-one basis to give them them 'me' time. Each dog will have their own area that they need work on, so it's inevitable you cannot effectively train them together all the time.

Of course there are also extra on-costs - double verything - food bills, kennel fees, vaccinations, dog-fur, muddy paw-prints etc etc!!

I guess much of the work it causes does to some extent depend on the breeds of dog you choose. Pups from the working or gundog group would need more training than some other breeds who are more inactive. Of course something small breeds like Chihuahuas or pugs would not be anything like the work of my Rott & GSD!!

Thanks to everyone for all the information and I agree with Luke... Lots of info from both sides of the coin!!!
Am I glad I asked???Hell Yes!! This has really helped us in deciding what we need to do so everyone is happy and has the best we can offer.
The plan has now changed to getting one puppy and then the second dog a year or so later.(do I hear people breathing a sigh of relief?) And yes.. we will be getting opposite sexes and yes...lots of walks,training and socialisation from the go-get taking pups growthplates into consideration! We have had experience with 2 dogs a year apart and it worked well although with both being female, there were some issues so its a boy and a girl this time.
Its so hard to wait! Home dosen't feel like home without a furry friend!!
Thanks again everyone!