One turntable with two arms, or two turntables with one each - which would you prefer?

Interesting topic! I have a related question for anyone who has mounted more than one arm on a TT. 

One of my friends is using a Transrotor TT which is capable of accepting 2 arms. He claims that just mounting a second arm would degrade the sound quality of the first arm. Another friend with a Micro 3000 also claims the weight of the second and third arm would affect the sound quality of the first arm. I am curious of how could that happen, maybe due to the change of weight distribution or the resonance point?

Any member has similar experience? 

How about one TT, one tonearm, one cartridge but with two styluses, huh? 
bet you never heard of one cartridge with two stylus, one MM and one MC

LOL!

For a question like this I must defer to Harry S. Truman.

He always said he preferred the one arm approach.

Particularly when speaking with economists.

It avoided the dreaded words "but on the other hand".

I use a VPI with a uni-pivot and two arm wands. Once set up I switch the wand and oly have to adjust the vta.

IMHO a silly question, unless you are rolling in money.

The best way to go is, one of the best turntables you can afford and one of the best arms you can afford with one of the best cartridges you can afford.

Do not buy two fair set ups at the expense of one excellent one. If you have to spend some time setting up cartridges, so be it. You are cheap labor. 

There are usually limits in terms of space so, two arms on one turntable is the most space effective and also the above argument still holds, one great table vs two not so great tables.