When ArcGIS.com displays metadata with multiple keywords, users viewing the metadata see a simple, non-repeated list of the keywords only when using FGDC CSDGM Metadata. Switching to any of the other metadata styles results in all keywords being repeatedly displayed. For instance, if there are five keywords entered for a resource and the metadata style is changed from FGDC CSDGM to any other style, the metadata is displayed with all five keywords on five different keyword lines.
I am not suggesting that all metadata styles be displayed the same, each style comes with its own groupings, display order, and information gathered. My idea is to ensure that ArcGIS.com handles the translation of metadata from one style to another consistently and does not result in unnecessary replication of information if an organization changes the metadata style they want to use.