One pair of speakers, two different speaker wire

I recently upgraded my speakers (same speaker line). Although I find them to be more refined, they have a tad less body. I decided to switch my speaker wire with a custom-made pair that’s been lying dormant for several years. It gave me the body I was looking for but a little less air and clarity on the top. I decided to use both pairs at the same time. Now I’m getting everything I was looking for, but I’m wondering if I’m doing any damage to my tube amplifier? Thanks for your response.
Again, thanks for your responses. However, let me clarify: I'm using two different pairs of speaker cables going to the same single speaker post. I'm not biwiring and using one pair on one set of speaker post and the other pair on the other post. Both pairs of speaker cable are going to the same single speaker terminal. Thanks!
Ah, I see. You won't damage anything, but I don't think it's going to make anything sound better either. The amp will put out the same power. The increased effective diameter may give you better bass response, depending on the gauge of the cables, but connecting to second set of speaker taps may change the load your amp sees, so that may affect the sound. Try running both from one tap and see if it sounds better/different
One pair of speakers, two different speaker wire
I have Martin Logan Monolith III's in a bi-amped way. I found oxygen free copper for the esl and silver for the bass to be the best of both worlds.
The other way around is too clinical for the esl mids highs and a bit soft/rich on the bass. It all depends on how you like you balance of your system in your room. 

Cheers George 
(S)He's not biamping. From what I understand there are two sets of speaker binding posts on the amp. a_passion then has both pairs running into one pair of binding posts on the amp.