Title says it all. It appears that Wordpress is stripping the second tag because the tag names are similar, I.E. if I add the tag "Google+" to a post and THEN add "Google" and then update the post, "Google" disappears. Vice versa if I added "Google" before "Google+".
I can't really change the tag name of "Google+" to "Google Plus" either, as it's more of a branding issue and it must be called "Google+." Anyone have any ideas? Should I submit this as a bug report?