The pair stormed to gold in the WB Tandem Time Trial, before going on to win the WB Tandem Road Race in a dramatic finish.
The Irish duo out-sprinted Poland to take the coveted world title, with Greece rounding off the podium as they took the bronze.
For Dunlevy, the two gold medals at these World Championships have been the culmination of everything she has worked for since claiming Time Trial gold at the Rio Paralympics last year.
“This is a massive thing,” said Dunlevy. “It’s everything I’ve worked for since Rio, but it’s also four years of hard work and we have come so close to a win in the road race before. Road racing is my favourite part, I get such a buzz from it.
“We worked incredibly hard for this gold medal.”
Dunlevy and McCrystal had earlier enjoyed a six-second advantage over silver medallists Lora Fachie and Corrie Hall of Great Britain to take gold in the Time Trial.