Two different cable pairs from amp into speakers

I have two different bi-wire cables with different strengths. One cable excells in the treble and mid-range and the other excells in the bass department. One cable is spade to spade and the other has bananas on both. My question is: Can I hook up both sets from my amp to my speakers (Piggy Back)? I want to use both biwire ends into the speaker and not let one bi-wire end hang loose. Will I get the best of both cables by combining the two or will the two different cables smear the sound? Maybe I should have each separate cable go to the different terminals on the speaker and not combine the cables? Thanks.
If you must mix and match cables on the same speakers, and your speakers have two sets of posts which provide for biwire/biamp connect each set of wires separately to the posts which you think they will work best with - be sure to pull out the jumper between the posts. You will probably not improve your sound by running both sets of cables to one set of posts, to the contrary, you would probably loose some of the transparency you now enjoy in the high end. The former method has been used by some, including myself long ago, as a form of passive tone control.
Newbee, My speakers have two sets of posts for bi-wiring and I have removed the solid metal jumpers. I was concerned primarily if this was safe and secondarily about the sound. Thanks, Jim
Some amps don't like some kinds of speaker wire - but if you have already used both of these wires individually w/out a problem I can't see that they should pose a problem for you. The differences in length shouldn't make much difference if its on the order of a couple of feet, but if you decide to make it a permanent change I would trim them down to match.
Done all the time. Put the cable with best highs on the hF posts. Other cable on the LF posts. I have done this with many brands of cables with good results.
I think, if I read correctly, that Jim has two sets of Bi-wire cables, and since one is all spades and the other is all bananas, he wants to run 4 spades and 4 bananas at each speaker. To gain the benefits of each cable. One on top of the other so to speak.

Why not, give it a try. If you dont like the way it sounds, so be it.

Maybe a local shop could reterminate for you. Spades and bananas on each cable at the speaker or conjoin the termination as a non-biwire. This way you can use them they way you like, one on bass the other on mid-treble.
Do both speaker cables need to be the same length?

The cables must be of similar length. If the two speaker cables are not close to each other in resistance, and inductance, the damping will be different. The capacitance will be different and the high frequency roll-off will be different. These electrical chracteristics affect the stereo image and image depth, as the two channels delicate balance has been disrupted.

There should be no differences in length for shorter lengths of more than a 2 to 1 ratio, and preferably the closer to the same, the better. Long runs will be more critical, and would need a closer match still.