I'm asking because I have dragonfruit varieties that need cross-pollination, but I suppose the question is valid for other plant species as well:
If a plant cannot be pollinated by its own pollen, but its own pollen gets brushed onto its stamen stigma, will the incompatible pollen then prevent successful pollination if compatible pollen is also brushed on?
e.g. will the bad pollen be "ignored" by the flower, or will it compete with the good pollen?
edit: fixed error