It's much harder to train two dogs that close in age MUCH harder.
You might get lulled into a false sense of security in the first 6-9 months, they will stick close to you and each other, you will think everyone here has been exaggerating - you won't bother doing intensive training with them both - you don't feel you need to, the training club insists you only bring one at a time to a class and you can't spare two evenings , but they come when you call and there's only a bit of naughtiness that's really quite cute.....,
Then their hormones kick in - and you find they ignore you and you end up walking them on flexi leads away from other dogs, never letting them off because they can't be trusted .... you can't keep an eye on two badly behaved dogs at once.
I have a family member with two young terrier siblings - I've heard that story unfold. Walks are no longer a pleasure with them.
I've got a 10month old small breed "teenager" with selective deafness ATM - walks have to be carefully managed. There are areas I simply don't go to now because there are too many opportunities for him to disappear into woodland. I cope because
a) we go to classes and he knows the commands even though he pretends he doesn't
b) the classes and the work we do in them reinforces the bond with him so I know he WILL come back and I know how to reinforce that recall as a positive thing and
c) I have a VERY well behaved 2.5yr old dog that he adores and follows.
Please don't get two youngsters close in age. Get one, train it well and then think about another.