Yes, you will find similiar chain supermarkets like Shoprite and Spar in Maputo, but prices are generally higher than those you would find in South Africa. You can also try Super Mar, which is a local supermarket.
A great way of saving money on groceries is to shop at local markets where you can get fresh, local produce that is in season without the hefty mark up found at supermarkets. Mercado Municpal, Mercado de Peixe (specialising in freshly caught fish) and Mercado de Xipamanine are great places for getting all your essential food stuff.
Good luck with your move to Mozambique.