Your Jira instance is configured in "Legacy mode":
https://confluence.atlassian.com/adminjiracloud/configuring-time-tracking-818578858.html
The Aha! to Jira integration does not support legacy mode. Aha! always tries to sync both the original and remaining fields in Jira so they match the values in Aha!
You should disable legacy mode in your Jira instance. It has been disabled by default in all Jira releases since 4.2.