2.39:1 *is* anamorphic. However, most movies are shot on spherical, not anamorphic...and if they are shooting anamorphic they are most certainly shooting 2880 x 2160 raw, not 2048 x 1536 ProRes.

DCI 2k standard is 2048 x 1080p, this is what 2k means when in reference to a movie master.