Hi VB123

I suggest you use sheet1 for all the registrations.
On sheet2 in column A list all the used numbers from column B of sheet1
only ones.
In column B of sheet2 you insert the formula
=SUMIF(Sheet1!B:B, A1, Sheet1:C:C)

Change the format for Column B of Sheet2 into "[h]:mm" to keep all
the hours shown.
Otherwise you will get the results in full days of 24 hours.

Hoop That Helps,

Wouter Magré.