Seeing Double Pokémon GO is a new Special Research story to coincide with Community Day May 2020.
The Special Research has a story related to Seedot, the Pokémon featured during this month's Community Day. To participate, you'll need a ticket you can buy from the shop for $1.
Seeing Double Pokémon GO: New Special Research Story Ticket Available Now
The event won't be playable until Community Day starts proper at 11 a.m on May 24. Completing the Special Research will get you three Incense, five Golden Razz Berries and some other rewards.
The story will follow Professor Willow learning about Seedot. You will have to evolve Seedot through to its final form, Shiftry while seeing the sorts of mischief it pulls.
The ticket's description in the item shop has the Special Research event run until 6 p.m. on May 24, while normal Community Day festivities an hour earlier.
You could technically play the research story whenever you want, but to claim the rewards you must play the Special Research story during the event window.
While you're out catching Seedot, you can also enjoy some other benefits like triple Catch XP and three hour long Incense. Your Great Buddy will also occasionally acquire items like PokéBalls for you during the event as well.