I know of two very well known pros who wouldn't think twice of doubling up .Had a lucky escape from using a dog last Autumn that is used doubled, owner full of shit and luckily backed out at last minute .Despite what we all think happens there are lads with substandard dogs that only stay when doubled up .It's cringy and embarrassing to watch BUT it does seperate those that make do, very clearly, from those who want the best and except no other .