Multiple slash regions and slash voices can exist at the same rhythmic positions. In multiple-voice contexts for slash voices and when slash regions overlap, Dorico Pro automatically changes their staff position and offset to accommodate all slashes as legibly as possible.
You can set default per-flow settings for the position and offset of slashes relative to other slashes at the same rhythmic positions on the Voices page in Notation Options.
Note
These options affect all rhythm slashes, including notes in slash voices as well as slash regions.
You can also control the positions of rhythm slashes relative to each other manually by changing their stem/voice direction and by changing their staff position.