PHP - Compare values ​in an array of objects

Question

I have an array of objects and i should compare which ones have two equal values.

The real case is this: i have a series of events, each of which has a date, a title and a speaker. Many of these events have multiple speakers and unfortunately i find a DB where they have decided to duplicate the event for each speaker.

So I have many events with the same date and the same title but different speaker. I would like to print only one event, with the list of speakers.

Here is a concrete example that is perhaps more intuitive. Starting situation:

Array ( 
    [0] => stdClass Object ( 
       [id] => 193 
       [date] => 2022-05-10 
       [title] => Lezione 1  
       [speaker] => Andrea 
    
    [1] => stdClass Object ( 
       [id] => 194 
       [date] => 2022-05-10 
       [title] => Lezione 1 
       [speaker] => Giorgio 
    
    [2] => stdClass Object ( 
       [id] => 195 
       [date] => 2022-05-10 
       [title] => Lezione 1  
       [speaker] => Giorgio 
    
    [3] => stdClass Object ( 
       [id] => 196 
       [date] => 2022-05-11 
       [title] => Lezione 2 
       [speaker] => Giorgio 
    
    [4] => stdClass Object ( 
       [id] => 197 
       [date] => 2022-05-11 
       [title] => Lezione 2 
       [speaker] => Giorgio

The result I would like to obtain is:

10 May 22 - Lezione 1 - Speaker: Andrea, Giorgio
11 May 22 - Lezione 2 - Speaker: Giorgio

I tried to use array_unique function but i can't get the desired result. Do you have any suggestions?