Just my thoughts on itI doubt there is a definitive answer that would satisfy everyone and doubt that it is worth he effort to try to clarify in any great detail  In some cases it is probably appropriate and actually used just like a surname in a legitimate but different broader sense than that used by our surname article and including patronymics in Iceland or elsewhere by the person  Thats probably especially true of radio personalities with an onair name that is actually two given names but sounds like a given name and a last name Ive seen that happen quite often and that happens with various other stage names and pen names that are derived from given names  But as a general rule no Some like AnnMargret make it clear by normally using a hyphen The problem of course is that our articles especially the stubs and substubs often do not have enough information to make it clear what is going on  If it is Mary Lou  or something of the sort common combinations of given names where the second one is much rarer as a surname especially if it includes the actual surname in the article itself it should clearly be under M in any category the redirect which should be there or a dummy one if needed because otherwise it would be a disambiguation page could be categorized if the full name were desired in some categories and when that is done a note on the article page is helpful  But in between there is a huge variety that youll likely get some arguments about no matter how it is done  A bigger problem is people with full names given in the article name yet indexed under just the first given name in all categories and there are lots of them Even worse are those Easter egg sortings under some nickname which doesnt even appear in the articles own name