Yes, as other have said "convergent evolution" is a concept in biology. However, in the case of hemoglobin this is unlikely because this gene is particularly l

Yes, as other have said "convergent evolution" is a concept in biology. However, in the case of hemoglobin this is unlikely because this gene is particularly large, and sensitive to change. As a result it is highly "conserved". That is, mutations in this gene are selected against at a high rate because they tend to be deleterious. To create a gene like hemoglobin, you'd need hundreds of mutations to develop a hemaglobin gene from raw material. It is possible, but unlikely that humans and sharks would have independently accrued the same exact mutations in the same places since their divergence to create the same gene. It is far more likely that since this gene is essential, it has remained mostly unchanged since the divergence of sharks/humans from their common ancestor.