I purchased a bright gold paint that has too much orange in it for my room. It is also too dark? I'm afraid that if I put white in it, it will still be too bright gold. I really needed something more "brass" duller than the gold I had mixed. Can I fix this? I bought 2 gallons; don't want to end up with six gallons of one color?

Why don't you try adding some yellow or even tan to it?
It might be a good idea to go to your local home depot, Lowe's, etc. and give the people there an idea of what color you want. They can mix the paints for you, rather than you having to spend money on other paints that might not give the paint you already have the right color change.