They are not actually redundant. If you examine some of the most basic of genetics you will see lots of discussion about dominate and recessive traits, this is essentially telling you that the different chromosomes you have inherited from different parents actually have different genes, or alleles. The interaction of these different alleles is what forms your phenotype. With out the extra information you can't survive for long.
A full range of chromosome aberrations lead to horrific diseases and cancers. Test for chromosome number are fairly common in many diseases such myeloid leukemia which is often caused by the loss of chromosomes in the cancerous tissue. You will find many people with various chromosome number abnormalities in these groups (in the cancerous tissue), there have been many studies I have seen that have examined chromosome numbers in these groups. A review will show that even in diseased tissue chromosome number is usually 46, and when it’s not its fatal.
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