View: Distinct list of all referenced entities
Create a view of events with relationship to the speakers and contextual filter to festival



For filtering duplicates you have to turn on aggregation as seen above and setup body aggregation settings: group column: format 



The contexual settings for festival are 



NOTE: To see preview for a festival put a festival node id in the contextual filter and press preview 

Finally you can put the view block display on content region or any other region from  structure &gt; block layout and the block with relevant event/speakers will be present when you visit a festival page