Importing brokerage QFX files into GnuCash

I’m trying to figure out how to import QFX files from my brokerage into GnuCash. I have read the documentation about investments here, but I’m having some problems getting it to work correctly. First problem:

I have several brokerage accounts set up in the following hierarchy:

Investments
  Brokerage Account #1
    Money Market Fund
    [various mutual funds]
  Brokerage Account #2
    Money Market Fund
    [various mutual funds]

The money market funds are the same fund across all accounts and are assigned to the same commodity. Money-market transactions for account #1 should show up under account #1; ditto for account #2. However, when I import QFX files of transactions, money-market transactions for account #2 are erroneously going into account #1, which happens to be the first one I set up in GnuCash.

Is this a known bug/limitation, or am I doing something wrong?