More than one leader in the same term？

[yc c]

 Log replication

Seeing the realization of sofa-raft, how did this scenario happen?

https://github.com/sofastack/sofa-jraft/blob/master/jraft-core/src/main/java/com/alipay/sofa/jraft/core/NodeImpl.java 1913

if (!serverId.equals(this.leaderId)) {
LOG.error("Another peer {} declares that it is the leader at term {} which was occupied by leader {}.",
serverId, this.currTerm, this.leaderId);
// Increase the term by 1 and make both leaders step down to minimize the  loss of split brain
stepDown(request.getTerm() + 1, false, new Status(RaftError.ELEADERCONFLICT,
"More than one leader in the same term."));
return AppendEntriesResponse.newBuilder() //
.setSuccess(false) //
.setTerm(request.getTerm() + 1) //
.build();

}