We have all made mistakes, i know i have made plenty, i kenneled two lurchers together and as you say never again, the pup kept trying to push his weight around with the old bull cross and kept nipping his ears until they bled, i should of noticed much quicker and thats my fault, one day the old dog throttled him unconcious...........Also kenneled two terrier saplings until they were a year old, bad bad idea, they had the odd grumble but one day world war three broke out and terriers can inflict a lot of damage on each other, i wouldn't advise kenneling two dogs together period................