I believe they are Universal. When you buy a CD on Universal Records or one of their affiliated labels, the spine sticker at the top of the case says (in a bluish-green) "UMVD".
UMVD is a fairly new (insofar as the actual name is concerned) umbrella distribution entity within the Universal family handling physical distribution for both Universal Studios Home Entertainment (including a deal to handle Dreamworks Home Entertainment distribution) and Universal Music Group. (An interesting aside: by selling Vivendi Universal Entertainment--which included the movie studio and TV operations but not UMG--to NBC recently, NBC Universal was created. I'm pretty sure UMVD fell under Universal Studios in the corporate org chart. So to the extent that UMVD is still distribbing for UMG [and I'm fairly sure they are], they're doing so even though the latter is still owned by the French.)
I second Peter's inquiry about which titles you're referring to, Marco. Perhaps you're confused by the fact that, thanks to Ted Turner, Warner owns a significant chunk of the MGM library?