Not because you submit variants, means every variant will be eligible for an ad auction at the same time.
Yes sometimes multiple variants can ben shown to the same user at once, this depends on the search term, the intent of the user, historical behavior, global user behavior and so on. Over 200 factors define what users see.
It is better to show more variants, as the equity you cover is greater, increasing the chances of a click, thus increasing your overall CTR.