I think I'm probably known as the littermate police on here

but I would strongly advise anyone against getting littermates especially same sex littermates.
Littermates are harder to train: they bond with each other - thus ignoring the humans - twice the mess, twice the expense - they socialise less with other dogs because they don't need other dogs because they have each other... when they get to adolescence they often do not like each other and there may be spats if not proper fights. They may gang up on other dogs together making you very unpopular in the park. Of course if you have time to walk them and socialise them separately - take them to separate training classes, train them separately etc - then you may not get any of the above problems.
Of course I am the voice of doom

(ask all the other littermate owners !) , and yours may be all hunky dory forever.... but they may not - and why not avoid the possibility of it going wrong by getting one puppy that will be easier to train and will see you as it's family rather than it's sibling.
Good luck in whatever you decide to do - btw a vet won't be able to tell anything about it's hereditary conditions - these -*test*-('")s should have been done before the parents were even "matched" - although tbh doesn't sound like much thought went into it....