Sometimes I like to random immediately, it's more entertaining that way, plus more gold, however since I like to do it immediately (full hero pool), recently I've been re-randoming accidentally because they are the same button, however if I recall correctly, before 7.00 UI, random and re-random were on opposite sides of the pick, quite far apart. All for very good reason as well. Right now with loading, it gets a bit tricky because there is a small lag right as all players officially connect and the screen enables randoming/picking/etc.