Hello Areen,

IgGrid offers Cell Merging feature out of the box. This feature allows users to merge cells in the column visually when they have the same value(display text). Simply enabling the feature will apply the cell merging on each sorted column. Alternatively, by setting the initalState property to merged the user can enable the features to try and merge cells when the grid is initialized. Some further reference about Cell Merging feature is available online:

Cell Merging Overview (igGrid)

Cell Merging API Reference

Additionally, a working sample demonstrating Cell Merging feature of igGrid in combination with Sorting feature where cells are merged on initial load is available online:

http://www.igniteui.com/grid/cell-merging

Please have a look at this information and let me know if you have any additional questions afterwards.