Except in pretty unusual cases - like Google having Blogger problems (which would be noted 99.99% of the time), if you blog a post or comment, it will be posted without publishing the post/comment more than once.
If the post/comment fails to appear. Hit F5 which refreshes/reloads the page.(F5 is the fifth function key - function keys run across the top row of your computer keyboard. In many software programs function keys do various things . . . or can be programmed to do various things. F1 almost always takes you to the help menu - no matter what program you are using.) If F5 doesn't work, wait a minute or two, Blogger may be really busy and it may take a bit for your comment/post to appear. My experience is that hitting F5 almost always "makes" the post/comment appear.
Whenever I come to the Uible blog, I always Hit F5 first. That way I get the newest "edition", not just what is saved in my cache.