Writer behavior when using Partitions in JSR352 Java Batch processing

Question

I have implemented a Java batch program using the JSR352 framework implementation available in the Websphere Liberty server container.

This Job is Chunk processing oriented

1. Reader - Read a data
2. Processor - Process it Writer
3. Writer - Write data in a file & update data in another file

Will the write operation in the Writer over-write each other when i create 2 partitions for this job ? or will both the partitions write output remain in the file without getting overwritten by the other ?