Originally Posted by CanadaDH

The financial institutions automatically report balances to the bureaus monthly on your open accounts, so both bureaus should have a full picture of what credit accounts you have open and your payment history with them. But that's not the same thing as pulling your credit report. I don't have any inside knowledge about what the various banks can and can't do, but from the 10+ years of credit reports I have saved on my computer (YMMV?), at least in my case, I've observed the banks stick with the same bureau when making credit checks.