With this error message Gerrit rejects to push a commit if the commit message footer of the pushed commit contains several Change-Id lines.
You can see the commit messages for existing commits in the history by doing a git log.
If it was the intention to rework a change and to push a new patch set, find the change in the Gerrit WebUI, copy its Change-Id line and use the copied Change-Id line instead of the existing Change-Id lines in the commit message of the commit for which the push is failing. How to do this is explained here.
If it was the intention to create a new change in Gerrit simply remove all Change-Id lines from the commit message of the commit for which the push is failing. How to do this is explained here. In case you have configured the commit hook a new Change-Id will be automatically generated and inserted.