Complex sentence: Until June 2012 Munchetty shared presenting duties with Komla Dumor until he left to present "Focus on Africa", and Komla Dumor has shared presenting duties with Naga Munchetty again since September 2012.
Split into simpler sentences: Until June 2012 Munchetty shared presenting duties with Komla Dumor until he left to present "Focus on Africa". And Komla Dumor has shared presenting duties with Naga Munchetty again since September 2012.