I was putting in some 500W PAR 64 spot lamps today. The old ones' were marked Sylvania, and the new one's were Phillips. The writing on both were absolutely identical. Same font, same type of printing. The ceramic insulator for the terminals had the exact same mold marks for both brands. I swear it was the exact same lamp with two different company names printed on it. I couldn't' see anything one bit different about either.
I say all that to say this... I bet your MR-16 lamps might well be GE's that are rebranded. Private branding is a big trend among all sorts of manufacturers. They'll sell their product any way they can.