Shared data dir for multiple postgresql nodes

Hi,
I'm asking this out of curiosity, if I have 2 postgres nodes on same server,
1. listening on port 5432
2. listening on port 5433

What issue's I might face if I do it like this? Assuming I'm doing this for
multimaster approach.

pg_ctl -D /data/postgres -o "-p 5432" -l /var/log/pg1 start

pg_ctl -D /data/postgres -o "-p 5433" -l /var/log/pg2 start

Happy to help :)
Prince Pathria Systems Architect Intern Evive +91 9478670472 goevive.com