You can build the transformed table in two steps.
Step 1: Generate list of unique IDs.
You can do this with the Advanced Filter tool. Select the column of IDs including the header and click Advanced Filter on the Data ribbon. Check the
Unique Records Only checkbox, and choose to
Copy to another location. Set the location for the output to go to and click OK. This will give you the list of unique IDs for the rows of your new table.
Step 2: Get certifications that match each ID in new columns.
You can use an array formula to return the matching certifications to the appropriate columns. In the row of the first record in your new table, enter the formula below, adjusted to match your sheet.
A1:B8 is the original data you provided,
F2 is the ID in the new table you are looking for certifications for, and
COLUMN()-6 equals 1 for the
Certif1 column, 2 for
Certif2 column (you'll have to adjust the subtraction term to match your data).
Once entered, select the cell, click inside the formula bar and press Ctrl+Shift+Enter. This will enter the formula as an array formula.
After doing this, fill the formula down the column. Then fill it over to as many columns as you need (just 3 for your sample data since
456 has 3 certifications). That should give you what you want.