Yes, there's truth to that. It would be more accurate to say that multiple females are at *high risk* of not getting along though, than to make blanket statements about will or will never.
The problems with bitches are several. First, the failure rate of multi-bitch combinations is higher than any other (male/female or male/male). So in the first instance, the risk of problems is highest. That's not to say that it never works - in many cases it does. But the risk of failure is not insignificant.
The second, and actually the biggest problem, is that *if* there are problems, then they're likely to be serious and dangerous ones. Bitch fights are very often fights to the death. Unlike dogs who generally just fight for supremacy and cool down once that's sorted out, bitches don't give a damn about who's the boss. They're fighting to get rid of the other bitch. Therefore, it may only end when one bitch is dead or otherwise removed. You break up one fight, they'll have another one tomorrow and again next week, and next month. See the problem?
Putting it into some amount of context, many breeders and rescues simply won't rehome a bitch into a household that already has one.
And just to complex things one step further, bitch fights rarely start before adulthood. Meaning that if you adopt an 8 month old bitch, you probably won't have any problems at all - until she hits 2+ years old. "Bonding" early is not a factor here - some of the worst bitch fights are mother/daughter or sisters. After the 2yr mark, then you might have problems - but there's little way of knowing whether you will or won't until that time. That's the real heartbreaker about bitch fighting... it doesn't happen early, so people have had both bitches for months or years before they're faced with a problem. And it's an extremely difficult problem to solve. In some cases, it cannot be resolved and you end either having to rehome one bitch, or live playing musical dogs, keeping the pair separated by at least one door 24/7.
Soo - where does that leave you? Nobody can guarantee to you that it will work, or that it won't work. It would, however, be rather rash to adopt this young bitch without fully considering what you'll do (behaviourists, keeping them separated, rehoming, etc) if it should happen that in a year or so's time the two begin to fight. It might not ever happen, but it's common to the point of notoriety, so you really do need to consider the 'what ifs' in this sort of situation.
