Can I repeat keywords in “Image Keywords”?

When I add a new module to my brand story, I’m supposed to add Image Keywords.

Can I add the same keyword multiple times? for example: “white ball black ball red ball” Or is it recommended I add the same keywords 1 time? for example: “white black red ball” Do image keywords need to be related to the actual photo? Or no, I can use Image Keywords to stuff additional keywords for search engine optimization?