Investigating REST API failures as described here:
https://confluence.atlassian.com/display/JIRAKB/CreateIssueMeta+returns+Duplicate+Key+error

It was revealed certain plugins will add the same custom field to multiple tabs in JIRA's screen scheme configuration. This only becomes a problem in recent JIRA versions.

Currently it is not possible to add a field to multiple tabs in the UI or via REST

Workaround

Please refer the documentation page for the workaround https://confluence.atlassian.com/display/JIRAKB/CreateIssueMeta+returns+Duplicate+Key+error