Why do organisms make one type of protein for a feature while other organisms make two?

It may mean that the two proteins evolve in slightly different directions, so that one version works better in one set of conditions and the other under different conditions.

Please note that the cost to the organism of making two proteins instead of one is minimal. Basically, it involves adding one coding gene to the tens of thousands of genes that are already there (assuming that the sum of the amounts of the two proteins is about the same as the amount of the original one protein).

Different versions of the same protein may also be made by differential splicing of the mRNA, or by the many mechanisms of post-translational modification.

Explanation:

im lazy so imma leave this out

For every gene, there may be several possible versions. Different genes carry instructions for making different proteins. If the gene copies are heterozygous, two types of protein are produced, if the gene copies are h0m0zyg0us, one type of protein is produced.

Explanation:

clinically, some people often have repeated allergies, eczema and respiratory infections or other parts of the infection, in this case, in addition to some routine tests such as tests for white blood cells, immunoglobulin series, lymphocyte subsets, etc., the five immune immunoglobulin tests are also necessary.