Complex sentence: The first, a Sainsbury's SavaCentre hypermarket was replaced with an Asda store in 2004, while a year later the then Allders was replaced with a Debenhams store in 2005.
Split into simpler sentences: The first, a Sainsbury's SavaCentre hypermarket was replaced with an Asda store in 2004. The then Allders was replaced with a Debenhams store in 2005.