Technically it is possible to get two clients open on one PC as of last build. However, these are not very viable options for MBing.
So yes, you can install a virtual machine and run a second copy of TOR but it probably isn't going to run very well, it probably won't even be playable.
Last build I leveled one character to 50, boxed two more to 50 and boxed another duo to 35. ISboxer running in multiple computer mode with two accounts is perfectly manageable. I ran my second character on a 4 year old gaming laptop that cost about 700 dollars then, it was a little slower in terms of loading but it was perfectly playable.
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