My current code over writes the cell values , while we iterate the cells in a foreach loop iteration.

int iGrpCount = 0;

public class MyGroup
{
public int RowIndex { get; set; } // Row Index
public int ColumnIndex { get; set; } // Column Index
public object ColumnValue { get; set; } // Column Value
public object SheetValue { get; set; } // Sheet Value
}

MyGroup objMgr = new MyGroup();
if (targetCell.RowIndex != templateRow.RowIndex)
{
objMyGrp[iGrpCount - 1].ColumnIndex = targetCell.ColumnIndex;
objMyGrp[iGrpCount - 1].ColumnValue = targetCell.Value.ToString();
objMyGrp[iGrpCount - 1].SheetValue = targetCell.ToString();
}

objMgr.RowIndex = targetCell.RowIndex;
objMgr.ColumnValue = targetCell.Value;
objMyGrp.Add(objMgr);
iGrpCount++;