Using different cables for Bi-Wiring

Is it advisable to use different cables (i.e different brands or different models) for bi-wiring or it is better to use both the same cables?
Sticking with the same manufacturer can me it a little less frustrating..Either can work..Its just takes time to find the right combo.. Copper bottom and silver top works well..........I have done it both ways with and without the same brand and , I like the silver on top ( highs ) and copper for low end very well...
Thanks Thorman. I note your reasons for using silver cables for the top end and copper cables for the bottom end. My concern in using different cables is whether it will cause an uneven frequency distribution?
Addressing your concern about different cables causing an uneven frequency distribution . . .

An engineer here at work has a bumper sticker on her car that says:

"Enlightment comes not from the answer, but from the question!"

I think that not only have you come up the perfect question, but you've also answered your own question at the same time. I think that you've talked it out to yourself.

That's why the common consenus is to use the same cables on the top and bottom.

Here's a link to Vandersteen's views on biwiring, which I first found in another thread on this forum: He recommends using the same wire for both runs, and using separate cables versus two within a single sleeve.
I would say the same cable but not necessarily the same gauge. DH labs bi-wire is 14g mid/tweet and 12g for the bass.
I believe you would find the same principles applied to the wiring inside a quality speaker, ie different gauge wiring is used for different drivers.
..i just recently biwired my piega c-40 speakers and before doing so the aforementioned richard vandersteen article and tried two different my case a crystal cable 'ultra' ..that i already had with an argento 'reference' cable and the sound was not good..then when i then used 2 seperate runs of the argento 'reference' cables the sound was superb...there probably is something to using the same cables for biwiring my case it certainly was the better combination...
I have often used different cables. Since the requirements for the two are different it is hard to see how using the exact same cables would be a great advantage. A much smaller gauge wire will work for the top end than the bottom. But as in every case with wire or cables results will vary with the system.