When the keyboard lights flashes once, it means the mobo is booting up normally. Otherwise, something is wrong with the mobo & it's not even checking the keyboard. There may be a short beep if a speaker is hooked up to the pc. It means ok.
So you're saying the bar animation is shown twice, but the windows logo/whatever on top is there the whole time? It's normal, depending on the config. Mine shows 3 times+.
Like I said, if you can log on to windows, don't worry about it.