Merge unique values if another cell matches - excel

Question

Merge all unique values if another cell matches. I already know how to merge cells but now some information is double. So what I would like to achieve is the following:
if column A has the same name, then all values given in column B for
that name must be given only ONCE in a new column.
My data has a row names and a row mode, for example (Row 1 is header)
A B
2 Brenda a
3 Brenda a
4 Joey a
5 Joey b
So I want:
E
2 a
3
4 a,b
5
I already did merge the modes in column 3:
=IF(A1<>A2;B2;C1&","&B2)
So I get in this example:
C
2 a
3 a,a
4 a
5 a,b
Then, I already did that only the first record get the additional modes in column 4:
=IF(A1=A2;"";INDEX(Sheet1!$C:$C;COUNTIF(Sheet1!$A:$A;$A2)+MATCH($A2;Sheet1!$A:$A;0) -1))
So I get in this example
D
2 a,a
3
4 a,b
5
Now I need a column that only uniques values are given for each name. So in this example:
E
2 a
3
4 a,b
5

Answer 1

If I am understanding how your data is structured, try this:
Add a new column, say column G for ease of explanation, that concatenates the name and mode in each row. So, cell G2="Brendaa", G3="Brendaa", G4="Joeya", G5="Joeyb", etc.
In your merge step you will test whether the current value in the cell for this column matches any previous values in the column: If no, you do the merge; if yes, you don't.
Your merge formula would change to something like the following:
=IF(A1<>A2,B2,IF(ISERROR(VLOOKUP(G2,G$1:G1,1,0)),C1&","&B2,""))
Then you would the next step as before.