Complex sentence: Previously called Qualiton, its name was changed to Hungaroton in the mid- 1960s, though the Qualiton brand remained as a label for operetta and gipsy music releases.
Split into simpler sentences: Previously called Qualiton, its name was changed to Hungaroton in the mid- 1960s. From then, the Qualiton brand remained as a label for operetta and gipsy music releases.