INDEX MATCH MATCH statement to look up the 1st occurrence, 2nd occurrence in a single cell

As you know, using INDEX MATCH MATCH will only return the first result it finds in my range of data (B10:U29)
I simply want to find a way to adjust my formula so all the occurrence appear in a single cell joined together with a comma

Hoping someone here might be able to assist and offer up a little advice as to what it is I'm missing here. Thanks in advance