Answer by taking a quote from the following article:

Armando Anthony "Chick" Corea (born June 12, 1941) is an American jazz pianist/electric keyboardist and composer. His compositions "Spain", "500 Miles High", "La Fiesta" and "Windows", are considered jazz standards. As a member of Miles Davis's band in the late 1960s, he participated in the birth of jazz fusion. In the 1970s he formed the fusion band Return to Forever.

In the 1970s Corea started working with vibraphonist Gary Burton, with whom he recorded several duet albums for ECM, including 1972's Crystal Silence. They reunited in 2006 for a concert tour. A new record called The New Crystal Silence was issued in 2008 and won a Grammy Award in 2009. The package includes a disc of duets and another disc with the Sydney Symphony Orchestra.  Toward the end of the 1970s, Corea embarked on a series of concerts and two albums with Hancock. These concerts were presented in elegant settings with both pianists dressed formally and performing on Yamaha concert grand pianos. The two traded playing each other's compositions, as well as pieces by other composers such as Bela Bartok. In 1982, Corea performed The Meeting, a live duet with the classical pianist Friedrich Gulda.  In December 2007 Corea recorded a duet album, The Enchantment, with banjoist Bela Fleck. Fleck and Corea toured extensively for the album in 2007. Fleck was nominated in the Best Instrumental Composition category at the 49th Grammy Awards for the track "Spectacle".  In 2008 Corea collaborated with Japanese pianist Hiromi Uehara on the live album Duet (Chick Corea and Hiromi). The duo played a concert at Tokyo's Budokan arena on April 30.  In 2015 Corea reprised the duet concert series with Hancock, again sticking to a dueling-piano format, though both also had synthesizers at their station. The first concert in this series was played at the Paramount Theatre in Seattle, and featured improvised music along with iconic songs from each of the duo and standards from other composers.

What style were the Hancock duets performed in?
In 2015 Corea reprised the duet concert series with Hancock, again sticking to a dueling-piano format, though both also had synthesizers at their station.