The earliest "production" two groove rifle of which I'm aware was the muzzleloading British Brunswick rifle of 1836.
It had a two groove barrel designed to take a special round ball with a "belt" cast around it's circumference sort of like the rings around Saturn. When loading, the belt had to be carefully fitted into the grooves of the barrel before the ball was rammed home (see the thumbnail at the bottom, this is one case where a picture is worth more than a thousand words. The top illustration is of the barrel and the bottom is the belted ball).
It was fairly accurate in its day, but the invention of the higher BC, more accurate, expanding base Minie' ball made it obsolescent fairly quickly. Despite that, production continued for over 50 years. It was even used by some Confederate troops during the War of Northern Aggression.
The British revived the two groove concept again in 1941 in an effort to speed up rifle production during WWII. They did extensive testing which showed no substantive differences in either accuracy or barrel life between their standard 5 groove rifling and the new 2 groove version, so it was accepted (but not required) as an alternative form of rifling for all .303 rifles.
After the US joined the war, US Army Ordinance "borrowed" the British research on two groove barrels. Unfortunately, in a mistaken effort to speed up production, the US Ordies REQUIRED two groove barrels. High Standard, who were producing all the barrels for Smith Corona '03's at the time, was using the new, faster "broach cut" (also called button rifling) method to rifle it's barrels rather than the older, slower to produce, cut rifling used by Remington.
Since High Standard had already designed, tested and produced four groove broaches and was using them successfully, they told the Army that the switch to two groove rifling would actually slow production and increase costs, since they'd have to design, test and produce all new two groove broaches before they could continue barrel production.
Back in those days there was a real war on and apparently US military procurement had not yet developed it's current penchant for sloth, procrastination and delay.
Rather than invoking a penalty clause and fining High Standard for failure to fulfill its contract, the Ordies simply rewrote the contracts and specs so that two groove barrels were required only where it would result in cost and/or time savings.
Regardless of the fact that tests showed production two groove barrels to be fully as accurate and long lasting as four groove types, there has always been a certain amount of prejudice against two groove barrels in this country, probably because people see them only as a cheap, second rate wartime expedient.
The truth is that the cut two groove barrels were actually more expensive and required much more time and skilled labor to produce than the button rifled four groove types.
An unfortunate result of the aversion to two groove barrels is that in the past, certain companies bought up the cheaper two groove barrels, cut two extra grooves in them, and sold them to unsuspecting buyers as original four groove barrels.
If you look at the altered barrels through a bore scope you can usually spot them fairly easily.
If they've been altered the finish in the "added" grooves is usually somewhat different from that of the originals. There may also be variations in the width of grooves or lands. Although USGI two groove barrels will usually shoot just as well as USGI four groove barrels, the "converted" four groove barrels are a total crap shoot because they never had to pass a USGI armorers inspection after the second set of grooves was cut. The altered barrels will usually have the acceptance stamp on them, but it was put there when they were two groove barrels.
Caveat Emptor!