A 17-year-old boy from Greater Manchester collapsed and died after taking drugs at Leeds Festival at almost the same time a 26-year-old man from Cornwall died after taking drugs at Creamfields in Cheshire. Neither victim has yet been identified.
Two 17-year-old youths, also from Manchester, have been arrested on drug offences in connection with the teenager's death in Wetherby.
According to Yorkshire Police the boy took drugs "immediately before he collapsed" shortly after 4.45pm on Saturday (27 August). He was rushed to hospital for emergency treatment, but was pronounced dead just before midnight.
Around 80,000 people attended the event headlined by Foals, Red Hot Chili Peppers and Biffy Clyro.
Police have not yet said what drug the youth took and published a warning to anyone thinking of consuming drugs.
Chief Superintendent Keith Gilert said: "Our thoughts are naturally with the family of the young man at this time. They were made aware of the incident by officers as soon as possible and were assisted to attend the hospital as quickly as possible. We will continue to support them through this difficult time."
Gilert added: "In partnership with the organisers, Festival Republic, we will continue to take action against those who risk the lives of others by supplying drugs. Anyone who has any concerns for either themselves or others at the Festival should contact Festival site or security staff or seek medical assistance."
The Creamfields fatality also took place on Saturday when a 26-year-old from Cornwall was found seriously ill at a campsite at the four-day dance festival. Pete Tong and Fatboy Slim are among those taking part in the festival, which is taking place at Daresbury, near Warrington.
A Cheshire Police spokesman, speaking to Mail Online, said: "Formal ID is to take place and we are awaiting the results of the post-mortem examination to establish the cause of death. Our thoughts are with his family at this time."