On the basis that you do mean pollinate and not propagate?....

If it's a species type plant (have not checked this particular one), normally you would get a better seed set if you have two or more plants of the same species to cross pollinate. Self-setting can work but the quantity of fertile seed may be low and produce undesirable characters in the resulting seedlings, usually less vigour and more prone to disease.

It does not work if all the plants are genetically identical of course such as if they are cuttings from one plant. They would have to be plants grown from seed so although the same species, each one genetically slightly different. This would always give the best results.