The huge difference between the invasion of Iraq & the action in Libya is that the US is acting in concert with the UN & a number of NATO allies.

Another difference is that the problem in Libya is obvious to all; while the presence of WMD in Iraq was open to dispute even before the invasion.

A third difference is the presence of an active opposition group in Libya (see return of downed pilots); while no one in Iraq suggested that US Troops would be welcomed as liberators.

You seem to see this as a replay of Iraq. I see it as similar to Korea (1950).

Are the Republicans being hypocritical? Sure. You can go back to the 1990s & find quotes from famous Republicans opposing Somalia or Kosovo that they called treason when used about Viet Nam. It all makes sense though once you accept that Republican Wars are good, Democratic Wars are bad.