決めること決めちゃって、その後は二手に分かれるよ？

、？

Let's decide what we need to decide, and after that we'll split into two groups, okay?

Literal

Decide things decide-[contracted-ちゃって], after [topic-は] two-groups-[at-に] divide-[polite-ます]-[question-よ]?

Casual group-planning speech. The repetition 決めること決めちゃって ('decide the things that need to be decided') uses the pre-nominal relative clause 決めること ('the things to decide') + the main verb 決める. This double use of the same verb is a common casual pattern for 'get X-ing done.' 二手に分かれる ('split into two groups') is a set phrase.