It's not uncommon. For the movies over the last 10+ years, there have been two distributions for the movies.
One is for pre-booking the ticket. In past years
2007: Deoxys
2008: Regigigas
2009: Shiny Pichu
2010: Shiny Raikou, Entei, Suicune
2011: Victini
2012: Keldeo
2013: Mewtwo
2014: Darkrai
2015: Arceus (including Shiny Arceus)
2016: Volcanion
2017: Ash Cap Pikachu
Then the in-cinema distributions
2007: Darkrai
2008: Shaymin
2009: Arceus
2010: Celebi
2011: Reshiram/Zekrom
2012: Meloetta
2013: Shiny Genesect
2014: Diancie
2015: Hoopa
2016: Greninja (Poll Winner), Magearna QR Code
2017: Marshadow