Homologous pairs of chromosomes carry the same genes. Although the chromosomes carry the same genes, each chromosome in a homologous pair could carry a different form of the gene, called an allele. One chromosome of each homologous pair is taken from each parent.
Organisms containing pairs of chromosomes that have the same genes are called diploid organisms. Humans have a pair of chromosomes carrying the same genes because this is a safety measure against errors and mutations. To illustrate, if an organism only had one chromosome, and the chromosome contained the gene coding for a defective protein, the organism may not be able to function normally and may die. On the other hand, if an organism had two chromosomes containing two of the same genes, even if one were defective, the gene on the other chromosome may code for the normal form of the protein, and the organism may survive based on the normal gene only.