Recently I was looking for a good quality split type 8ton/hr floor standing package air conditioners and find out that most of the manufacturers are making these type of air conditioners with dual independent refrigeration circuits both in the Indoor and outdoor unit . These air conditioners the built with two scroll compressors rather than one 8ton/hr compressor. most of my experience is with single compressor air conditioners . My questions are:
1) Which is the better system for 8ton/hr split type air conditioning unit? is it with single compressor or double compressor?
2) Which system is better for long pipe length distance?
3) does two compressor starts at a same time or one after another?

Can any body help?