Renaming duplicated elements

ProjectMapper.cs

var groupedLines = lines.GroupBy(x => new { x.TRACType, x.Description })
            .Where(z => z.Count() > 1)
            .Select(x => x);
        foreach (var grp in groupedLines)
        {
            int idx = 1;
            foreach (BudgetLine budgetLine in grp)
            {
                budgetLine.Description = $"{budgetLine.Description} {idx}";
                idx++;
            }
        }